In this medical diagnostic apparatus (10), a host circuit board (13) acquires comprehensive update data containing update data for all attachable circuit boards, specifies client circuit boards (11, 12, 14, 15, 16, 17) attached to the medical diagnostic apparatus (10), specifies update data corresponding to the client circuit board in the comprehensive update data, determines whether or not update processing should be performed on the basis of, for example, a program of the client circuit board and the update data, and transmits at least the specified update data to the client circuit board upon determining that the update processing should be performed. The client circuit board performs the update processing on the basis of the transmitted update data.
