To provide a technology for performing vector interpolation with respect to a smaller part in a block.

A method includes a step of detecting a motion vector of an object inside a frame image by block matching processing between input frame images and a step of creating an interpolation frame by using the detected motion frame to insert it between the input frame images. The block matching processing is an interpolation frame creating method which includes: a first adoption step of adopting a motion vector candidate as a motion vector to be used in creating the interpolation block when only one motion vector candidate is detected with respect to an interpolation block inside the interpolation frame; and a second adoption step of adopting a motion vector of existing reliability among a plurality of detected motion vector candidates as a motion vector to be used in creating a part of the interpolation block.