A log acquisition method which can easily acquire processing logs of software, and can reduce the number of processes required to analyze bugs is provided. More specifically, a log acquisition method for a program having functions, includes a step of identifying a designated one of functions in an OS which are called upon execution of the program, and a step of rewriting the address of the loaded functions that execute predetermined processes and the address of the designated function in the OS to that of a function for log acquisition. The function for log acquisition includes a step of calling the functions that execute predetermined processes and the designated function in the OS and passing the execution result of the called functions to the program, and a step of recording predetermined information upon calling the functions that execute predetermined processes and the designated function in the OS, and predetermined information upon receiving the result.