To provide a device and method for measuring human physical activity level, and its computer program.

A first movement of an upper limb is detected by a movement sensor during a pre-determined measurement period. A second movement of the upper limb, following the first movement, is detected during another predetermined threshold period after the passage, and then removed through the filtering. When the first movement is not recognized as a periodical activity, a third movement of the upper limb, following the first movement, is detected during a prescribed threshold period extended from the passage, and then removed through the filtering.