1. A motion detection apparatus for detecting a motion of an object, comprising: an image pickup section picking up a motion image and successively clipping a time series of frame images; a feature extracting section extracting a first feature area, representing a feature of the object, from a first frame image among the time series of frame images; a feature area standardizing section standardizing a size of the first feature area to be set as a first standardized feature area; a mask generating section setting an area on the first frame image, which is a complement of the first standardized feature area, as a first masked area; a balloting section resetting a count value on the first masked area and counting up a count value of a first non-masked area that is a complement of the first masked area; and a shift speed calculating section calculating a shift direction and shift speed of the first feature area based on a gradient of a count value accumulated for the time series of frame images.