A motion device and a movement device, in each of which the external dimension perpendicular to the direction in which a track body extends is kept as small as possible to reduce the size of the device. The motion device (1) has the track body (2) and a mobile body (3) inserted through the track body (2) and reciprocatably guided in the extension direction (L) of the track body (2). Cylindrical projections (6a) are pivotally supported by bearings (7) at the ends of the mobile body (3). The projections (6a) project in the extension direction (L) and are inserted through the track body (2). The external dimension of a projection (6a), measured in the direction perpendicular to the extension direction (L), from the track body (2) as the center is smaller than the external dimension of the mobile body (3).
