diff --git a/src/main/java/cactusServer/entities/Character.java b/src/main/java/cactusServer/entities/Character.java
index 2661bc2..d4328f7 100644
--- a/src/main/java/cactusServer/entities/Character.java
+++ b/src/main/java/cactusServer/entities/Character.java
@@ -77,7 +77,7 @@
 	}
 
 	public Map<String, Item> createItem(String name, int amount) {
-		String id = createUniqueId(UNIQUE_ID_LENGTH, itemMap.keySet());
+		String id = new RandomStringGenerator().createUniqueString(UNIQUE_ID_LENGTH, RandomStringGenerator.ALPHA_NUMERIC, itemMap.keySet());
 		Item item = new Item(name, amount);
 		itemMap.put(id, item);
 		return new HashMap<String, Item>() {
@@ -92,24 +92,4 @@
 	public Item destroyItem(String itemId) {
 		return itemMap.remove(itemId);
 	}
-	
-	private String createUniqueId(int length, Set<String> idSet) {
-		String id;
-		do {
-			id = createRandomId(length);
-		} while (checkId(id, idSet));
-		return id;
-	}
-	
-	private boolean checkId(String id, Set<String> idSet) {
-		return idSet.contains(id);
-	}
-	
-	private String createRandomId(int length) {
-		StringBuilder id = new StringBuilder("");
-		do {
-			id.append(UUID.randomUUID().toString());
-		} while (id.length() < length);
-		return id.substring(0, length);
-	}
 }
diff --git a/src/main/java/cactusServer/entities/Instance.java b/src/main/java/cactusServer/entities/Instance.java
index a1fb2c5..611dbd8 100644
--- a/src/main/java/cactusServer/entities/Instance.java
+++ b/src/main/java/cactusServer/entities/Instance.java
@@ -29,6 +29,7 @@
 	@JSONHint(ignore = true) private HashMap<String, Object> objMap = new HashMap<>();
 	@JSONHint(ignore = true) private HashMap<String, Character> characterMap = new HashMap<>();
 	@JSONHint(ignore = true) private static final int UNIQUE_ID_LENGTH = 12;
+	private static final String ALPHANUMERIC = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
 	
 	/**
 	 * (�����͌����_�ł̉��̂���)
@@ -88,7 +89,7 @@
 	}
 
 	public Map<String, Area> createArea(String areaId, String name, Plain[] regions, HashSet<Allowed> permissions) {
-		String id = createUniqueId(UNIQUE_ID_LENGTH, areaMap.keySet());
+		String id = new RandomStringGenerator().createUniqueString(UNIQUE_ID_LENGTH, RandomStringGenerator.ALPHA_NUMERIC, areaMap.keySet());
 		Area area = new Area(name, regions, permissions);
 		areaMap.put(id, area);
 		return new HashMap<String, Area>() {
@@ -97,7 +98,7 @@
 	}
 	
 	public Map<String, Object> createObject(String objId, Position3D position, Velocity3D velocity, AngularVelocity3D angularVelocity, Object.Attribute attribute) {
-		String id = createUniqueId(UNIQUE_ID_LENGTH, objMap.keySet());
+		String id = new RandomStringGenerator().createUniqueString(UNIQUE_ID_LENGTH, RandomStringGenerator.ALPHA_NUMERIC, objMap.keySet());
 		Object object = new Object(position, velocity, angularVelocity, attribute);
 		objMap.put(id, object);
 		return new HashMap<String, Object>() {
@@ -106,7 +107,7 @@
 	}
 	
 	public Map<String, Character> createCharacter(URI accountURI, String name, Position3D position, String areaId, boolean isActive) {
-		String id = createUniqueId(UNIQUE_ID_LENGTH, characterMap.keySet());
+		String id = new RandomStringGenerator().createUniqueString(UNIQUE_ID_LENGTH, RandomStringGenerator.ALPHA_NUMERIC, characterMap.keySet());
 		Character character = new Character(accountURI, name, position, areaId, isActive);
 		characterMap.put(id, character);
 		return new HashMap<String, Character>() {
@@ -126,26 +127,6 @@
 		return objMap.remove(objId);
 	}
 	
-	private String createUniqueId(int length, Set<String> idSet) {
-		String id;
-		do {
-			id = createRandomId(length);
-		} while (checkId(id, idSet));
-		return id;
-	}
-	
-	private boolean checkId(String id, Set<String> idSet) {
-		return idSet.contains(id);
-	}
-	
-	private String createRandomId(int length) {
-		StringBuilder id = new StringBuilder("");
-		do {
-			id.append(UUID.randomUUID().toString());
-		} while (id.length() < length);
-		return id.substring(0, length);
-	}
-
 	public static enum State {
 		AVAILABLE, MAINTENANCE;
 	}
diff --git a/src/main/java/cactusServer/models/Instances.java b/src/main/java/cactusServer/models/Instances.java
index 61cb588..f829b43 100644
--- a/src/main/java/cactusServer/models/Instances.java
+++ b/src/main/java/cactusServer/models/Instances.java
@@ -6,7 +6,10 @@
 import java.util.Set;
 import java.util.UUID;
 
+import org.apache.commons.lang3.RandomStringUtils;
+
 import cactusServer.entities.Instance;
+import cactusServer.entities.RandomStringGenerator;
 import net.arnx.jsonic.JSONHint;
 
 /**
@@ -19,6 +22,7 @@
 	private static Instances theInstance = null;
 	private HashMap<String, Instance> instanceMap = new HashMap<>(); // instance��ID�Ǝ��̂��Ǘ�
 	private static final int UNIQUE_ID_LENGTH = 12;
+	private static final String ALPHANUMERIC = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
 	
 	private Instances() {
 
@@ -44,7 +48,7 @@
 	 * @return �V�����쐬���ꂽID��Instance��Map
 	 */
 	public Map<String, Instance> createInstance(String name) {
-		String id = createUniqueId(UNIQUE_ID_LENGTH, instanceMap.keySet());
+		String id = new RandomStringGenerator().createUniqueString(UNIQUE_ID_LENGTH, RandomStringGenerator.ALPHA_NUMERIC, instanceMap.keySet());
 		Instance instance = new Instance(name, Instance.State.AVAILABLE);
 		instanceMap.put(id, instance);
 		return new HashMap<String, Instance>() {
@@ -86,25 +90,4 @@
 	public Instance destroyInstance(String instanceId) {
 		return instanceMap.remove(instanceId);
 	}
-	
-	private String createUniqueId(int length, Set<String> idSet) {
-		String id;
-		do {
-			id = createRandomId(length);
-		} while (checkId(id, idSet));
-		return id;
-	}
-	
-	private boolean checkId(String id, Set<String> idSet) {
-		return idSet.contains(id);
-	}
-	
-	private String createRandomId(int length) {
-		StringBuilder id = new StringBuilder("");
-		do {
-			id.append(UUID.randomUUID().toString());
-		} while (id.length() < length);
-		return id.substring(0, length);
-	}
-
 }