1. A method for acquiring a comparative image of a measured image measured from a semiconductor device and a reference measured image measured from a reference semiconductor device, the method comprising: acquiring the measured image measured from the semiconductor device and a first pattern image showing a pattern of the semiconductor device corresponding to the measured image; acquiring the reference measured image measured from the reference semiconductor device being the semiconductor device or a semiconductor device different from the semiconductor device and a second pattern image showing a pattern of the reference semiconductor device corresponding to the reference measured image; acquiring matching information indicating a correlation of the first pattern image and the second pattern image based on the first pattern image and the second pattern image; and determining a difference of the measured image and the reference measured image based on the matching information to acquire the comparative image.