Abstract the misconceptions experienced by students, and this research can be used This study aims to produce a good diagnostic test to explore students' misconceptions about straight motion material. The form of the research is a development research that is directed to produce a diagnostic test in the form of multiple choice with three choices of answers in the SMA straight motion material that is used to detect the students"™ misconception. The limited scale trial was conducted in class X MIA 1 Senior High School 7 Pontianak. Whereas the largescale trials was conducted in class X MIA 3 and MIA 4 Senior High School 2 Pontianak and students of class X MIA 1 and MIA 2 Senior High School 8 Pontianak. The results of this study is in the form of diagnostic tests that meet the characteristics of a good diagnostic test with 18 questions which was developed based on the misconceptions experienced by the students with difficulty level 0.31-1.00, readability level 4.72, level of content"™s validation 0.70 and reliability 0.80. The findings of this study are expected to help physics teachers to overcome as further research material for other students of physics education programs. Keywords: Diagnostic Test, Straight Motion
