A simulation method includes obtaining an execution log generated while a predetermined processing is executed by simulating a series of operations in a test model that is a modeled version of a test target device by causing a predetermined processing to be executed in the test model, extracting a processing unit log constituted by a predetermined processing unit from the execution log obtained in the obtaining, and simulating an operation in which processing corresponding to the processing unit log extracted in the extracting is executed in a test model in which a part of function of the test target device is modified, the operation being simulated on the basis of a setting condition set by a user.