The topic of the study is Effect of instructional material on the academic achievement of physics student in senior secondary school student in Udi Local Government Area of Enugu State. The purpose of the study was to determine the effect of instructional material on the academic achievement of physics student. The work was a pre-test, post-test of control and experimental group. The research design is quasi-experimental design. The researcher formulated two research question and two hypotheses that guided the study. The researcher used Physics achievement test as an instrument of data collection the population of the study is 525 and the sample size is 80 in four selected school government secondary schools in Udi Local Government Area of Enugu State. The data collected was analyzed using mean, standard deviation for the research questions and ANCOVA for the hypothesis analysis. The validity is face and content validity. The reliability is tested to be 1.0 using Karl Pearson Correlation The study revealed that the academic achievement of physics student depends on the use of instructional material and teacher’s attitude to arose the interest of the physics student. Result also showed that there is significant different between male and female student taught with instructional material because physics is seen as hard course. The following recommendations were made, government should organize workshop and seminar for teachers on the use of instructional material to arouse the interest of the student and educational planners should implement it in the school curriculum among others.