Abstract
Adjective clause is a clause that modifies noun or noun phrase. It is important to be mastered because it is known for its usefulness, complex structures and grammatical importance. Unfortunately, many students found it difficult to construct correct adjective clauses. Students did not know the concept, function of relative pronoun and the use of adjective clause. Furthermore, students also ignored in the use of comma as giving additional information to the meaning of the sentence.This study is aimed to describe and analyze second year students’ grammatical achievements in constructing restrictive and non-restrictive adjective clause. There were 30 students from K1,K2,K3,K4,NK1,NK2 as the research samples. Proportionate stratified random sampling was used as the sampling technique to collect the data. This descriptive study used grammar test as the research instrument; 9 items were for restrictive and 9 items were for non-restrictive. The findings were students’ grammatical achievement in constructing restrictive were poor (47,02%) and students’ grammatical achievement in constructing non-restrictive were very poor (39,25%).