The aim of this study were to find out whether there is significant
correlation between students’ reading interest in academic books and their
vocabulary achievement at the fifth semester of IAIN Syaikh Abdurrahman
Siddik. The population in this study was all of fifth semester students at IAIN
Syaikh Abdurrahman Siddik with a total population of 30 students. The sample in this study were class 5A 7 students and 5B 8 students with a total of 15 students.

The method of this study was quantitative method and the technique that
used was correlational technique. In collecting the data, the researcher used
questionnaire about students’ reading interest in academic books and vocabulary test. Both of the data were calculated with SPSS version 22 program. The result shows that is a positive correlational between students’ reading interest in academic books and their vocabulary achievement. It proved by the rxy (0.776) which bigger than rtable (0.514) in the degree significance 5%. In considered that the researcher’s hypothesis (Ha) was accepted and null hypothesis (Ho) was rejected.

Afterwards, the researcher concluded that there was strong correlation between students’ reading interest and their vocabulary achievement at IAIN Syaikh Abdurrahman Siddik, and the correlation was positive. It means that students’ reading interest had strong contribution in their vocabulary achievement.