Moving image encoding method and moving image encoding device

A moving image encoding method comprising:

• encoding a difference between a first moving image and a corresponding motion compensated prediction image;
• and
• encoding a difference between a second moving image and a corresponding motion compensated prediction image,
• wherein, when prediction processing for the first moving image and prediction processing for the second moving image whose frame rate is smaller than a frame rate of the first moving image are simultaneously performed, an arithmetic amount is reduced only for the first moving image, and prediction processing is performed,
• the method further comprises:
• changing, in order not to simultaneously perform P picture prediction processing for the first moving image and the prediction processing for the second moving image, a group of pictures (GOP) structure in accordance with the P picture prediction processing,
• wherein, in the changing of the GOP structure, a timing of the P picture prediction processing is determined on the basis of a value obtained by dividing the frame rate of the first moving image by a greatest common divisor of each of the frame rates of the first and second moving images.