A log acquisition method is provided that allows a processing log of software to readily be acquired and reduces the man-hours needed for analyzing a bug. The log acquisition method is a method for acquiring a runtime log of a program including a function, comprising the step of changing the address of the function loaded to the address of a function for log acquisition and selecting the function, wherein the function for log acquisition comprises the steps of: calling the function the log of which is to be acquired to cause a predetermined process to be executed, receiving the result of the execution, and passing said result to said program, recording given information when calling the address of the selected function, and recording given information when receiving the result of the execution of the selected function.