PURPOSE: To provide a simple command input method by identifying the command corresponding to the motion vector included in an input image.

CONSTITUTION: The video signals inputted through a video input terminal 10 are inputted to a motion vector detecting circuit 11. The circuit 11 decomposes an image into the blocks composed of plural picture elements respectively and detects the motion vector at every block. These detected vectors are outputted at every frame and stored in a memory 12 in the period of several frames. A command deciding circuit 13 collates the vector value read out of the memory 12 with a pattern read out of a command analyzing dictionary 14 and identifies a registered command. Thus the decided command is outputted through a command output terminal 15. That is, the command can be inputted by using an input image and a simple command input means is obtained for an image processor.