An ultrasonic imaging apparatus comprising the main body containing a transmission system, a reception system composed of a plurality of receiving sections, a signal processing system, a display system, and a first connector, a probe unit containing a plurality of transducers, a second connector for connecting the probe unit to the first connector of the main body in a detachable manner, a memory in stalled in the second connector for storing data to calibrate at least one of the sensitivity and phase characteristics for each of the plurality of transducers, and a calibration circuit installed in the main body for retrieving stored data from the memory and calibrating one of sensitivity and phase characteristics for each of the plurality of receiving sections of the reception system.