To provide a medical apparatus with which the possibility of a collision is detected between a subject and the medical apparatus (for example, an MRI apparatus, a CT apparatus, or the like).

An MRI apparatus 100 has laser sensors 3A-3I arranged along an upper edge 11B of the opening 11A of a bore 11 and a determination section 32 for determining a possibility of collision on the basis of electric signals 3a-3i from the laser sensors 3A-3I. When the determination section 32 determines that collision is possible, an alarm lamp 33 turns on in response to an alarm signal Salarm from the determination section 32, and a cradle 21 stops in response to a cradle stop signal Sstop from the determination section 32.