This study aims to determine the effect of inquiry learning model on student physics achievement in junior high school. The method used is experimental research. The sample used are; grade VII-D students as many as 27 people as control class, and level VII-G as many as 27 people as experimental class. The sample selection was done by purposive sampling technique. The data were collected by pre-test and post-test in both classes. The average pre-test in the experimental class is 28.04 and 30.11 for the control class. The average post-test score in the experimental class is 74.41 and 69.26 for the control class. The analysis result using t-test obtained t-test of 1.82 and t-table is 1.67. The value of t-test is greater than t-table at 5% and dk is 52. We conclude that there has been a significant influence of inquiry learning model on physics learning achievement.