An image analyzer (12) of an input device (1) analyzes images acquired by an image acquirer (11) and extracts image areas representing a user's body parts. A coordinate extractor (13) extracts, from the image areas representing body parts, coordinates of feature points on body parts, and generates body motion information (200d) representing trajectories of motions of body parts. When determined that predetermined body motions are performed based on the body motion information (200d), a body motion determiner (15) detects center coordinates of trajectory shapes of the predetermined body motions. A start coordinate detector (16) detects start coordinates of the predetermined body motions based on the body motion information (200d). A command generator (17) generates, based on positional relationships between points defined by the center coordinates and points defined by the start coordinates, command information (100a) representing commands and transmits generated commands information (100a) to a target device (100).