1. An ultrasonic Doppler diagnostic equipment comprising; a transmission/reception unitunit which transmits and receives ultrasounds to and from a patient, a Doppler signal detection unit which detects Doppler signals at a desired range gate position, from reception signals obtained by said transmission/reception unit, a spectrum measurement unit which measures a Doppler spectrum on the basis of the Doppler signals detected by said Doppler signal detection unit, a decision unit which determines processing conditions of an average process on the basis of power values of spectral components in the Doppler spectrum measured by said spectrum measurement unit, an average process unit which performs the average process of the Doppler spectrum on the basis of the processing conditions determined by said decision unit, and a display unit which displays a Doppler spectral image on the basis of the Doppler spectrum subjected to the average process by said average process unit.