An ultrasonic observing apparatus according to the present invention comprises a machine-side connector receptacle, an electronics-side connector receptacle, a mechanical echo signal detecting unit for detecting an echo signal obtained by receiving waves in a mechanical scanning ultrasonic probe connecting to the machine-side connector receptacle, an electronic echo signal detecting unit for detecting an echo signal obtained by receiving waves in an electronic scanning ultrasonic endoscope connecting to the electronics-side connector receptacle, and a signal processing unit for performing signal processing on the echo signal from the mechanical echo signal detecting unit and the echo signal from the electronic echo signal detecting unit.
