diff --git a/src/main/java/models/terms/Dependency.java b/src/main/java/models/terms/Dependency.java
index 6783130..3f02383 100644
--- a/src/main/java/models/terms/Dependency.java
+++ b/src/main/java/models/terms/Dependency.java
@@ -20,6 +20,9 @@
 		this.dependingTerm = dependingTerm;
 		this.dependedTerms = dependedTerms;
 		this.addChild(dependingTerm);
+		if (dependingTerm.getOrder() > getOrder() - 1) {
+			throw new SyntaxException("dependingTerm's order must be less than" + (getOrder() + 1) + ", but " + dependingTerm + "'s order is " + dependingTerm.getOrder());
+		}
 		for (EvaluatableTerm dependedTerm: dependedTerms) {
 			this.addChild(dependedTerm);
 			if (dependedTerm.getOrder() != getOrder()) {