This study aimed to examine the contents of a Japanese course for learners majoring in science or engineering. In this study, the usage of the compound case particle 'niyotte' and its variants in a physics textbook were analyzed. The findings were that (1) 'niyotte' is frequently used to demonstrate logic in physics; (2) the meaning of 'niyotte' differs when indicating preconditions and definitions, when doing a calculation according to a formula, as well as when describing causal relationships. Therefore, the usage of the compound case particle 'niyotte' needs to be studied in connection with the logical structure of physics.
