A technique is disclosed for downsizing a motor drive unit (MDU) and improving durability in an imaging apparatus for diagnosis. In the motor drive unit, when a catheter connector is connected, a motor drive unit connector (MDU connector) for being connected to the catheter connector has a shape which accommodates the catheter connector in order to optically connect an optical fiber of a cylindrical member of a catheter and an optical fiber leading from the imaging apparatus for diagnosis to each other, and in order to connect an electrical contact portion of the catheter and an optical/electrical signal line leading from the imaging apparatus for diagnosis to each other. Then, the motor drive unit has a structure, which supports a center position of an end portion of the optical fiber exposed from the cylindrical member of the catheter, as a rotation center position of an imaging core.
