X-ray computed tomographic device, top plate control device and top plate control method

An X-ray computed tomographic device (1) according to an embodiment comprises: a gantry (100) which includes an X-ray tube (107) that generates X-rays and an X-ray detector (113) that detects X-rays that pass through a subject; a bed (1000) which is disposed on a front side of the gantry (100) and has a top plate (115) that is movable toward an opening (117) of the gantry; an input unit (600) for inputting an imaging plan relating to the imaging of the subject; and a control unit (800) which, when an imaging plan is input from the input unit (600) to image a portion of the subject inserted into the opening (117) from a rear side of the gantry (100), controls the bed (1000) so as to limit movement of the top plate (115).