An ultrasound diagnostic system comprising first (2B, 2C) and second (2A, 2D) ultrasound probes including first and second ultrasound transducers driven respectively by first and second different ultrasound scanning systems, wherein the first ultrasound probe (2B, 2C) includes a first ultrasound transducer (14B, 14C) of a first mechanical scanning system, and the second probe (2A, 2D) includes a second ultrasound transducer of a second electronic scanning system and an ultrasound image processing apparatus, characterised by said ultrasound image processing apparatus comprising: first and second connecting portions to which the first (2B, 2C) and second (2A, 2D) ultrasound probes are removably connected; and an ultrasound image signal processing means (32A, 32B) adapted to perform signal processings to generate first moving and second moving ultrasound images corresponding to the first mechanical scanning system and the second ultrasound electronic scanning system from ultrasound signals received by the first and second ultrasound transducers connected to the first and second connecting portions, wherein the ultrasound image signal processing means (32A, 32B) includes first and second transmission means adapted to output first (Sd) and second (Sc) transmission pulses for alternately driving the first and second ultrasound transducers at predetermined intervals to alternately transmit ultrasound, and wherein the ultrasound image signal processing means (32A, 32B) is adapted to generate the first moving and the second moving ultrasound images from first and second ultrasound signals outputted by the first and second ultrasound transducers receiving reflected ultrasound in alternately driving the first and second transducers, the ultrasound image processing apparatus further comprising: a first transmitting and receiving circuit including the first transmission means to which the first ultrasound transducer is connected via a first signal wire adapted to transmit the first transmission pulse and receive the first ultrasound signal, the first transmitting and receiving circuit being adapted to transmit and receive ultrasound by the first ultrasound transducer; and a second transmitting and receiving circuit including the second transmission means to which the second ultrasound transducer is connected via a second signal wire adapted to transmit the second transmission pulse and receive the second ultrasound signal, the second transmitting and receiving circuit being adapted to transmit and receive ultrasound by the second ultrasound transducer; and control means for controlling operations of the first and second transmitting and receiving circuits so that periods of transmitting and receiving by the first and second ultrasound transducers do not overlap, wherein a user-operated freeze switch is provided on a grasping portion of the second ultrasound probe, said switch being connected to contacts of a connector of the second ultrasound probe, wherein the connector is removably connected to a connector receptacle in the ultrasound image processing apparatus, and the control means is further configured to perform control so that, by an instruction operation of the freeze switch, transmission by at least the second ultrasound transducer is stopped and an ultrasound image obtained by the second ultrasound transducer corresponding to the stopping is displayed as a still image, and all of the periods of transmitting and receiving are used as periods of transmitting and receiving by the first ultrasound transducer and ultrasound images obtained only by transmitting and receiving by the first ultrasound transducer are displayed as moving images. a first transmitting and receiving circuit including the first transmission means to which the first ultrasound transducer is connected via a first signal wire adapted to transmit the first transmission pulse and receive the first ultrasound signal, the first transmitting and receiving circuit being adapted to transmit and receive ultrasound by the first ultrasound transducer; and a second transmitting and receiving circuit including the second transmission means to which the second ultrasound transducer is connected via a second signal wire adapted to transmit the second transmission pulse and receive the second ultrasound signal, the second transmitting and receiving circuit being adapted to transmit and receive ultrasound by the second ultrasound transducer; and control means for controlling operations of the first and second transmitting and receiving circuits so that periods of transmitting and receiving by the first and second ultrasound transducers do not overlap, wherein a user-operated freeze switch is provided on a grasping portion of the second ultrasound probe, said switch being connected to contacts of a connector of the second ultrasound probe, wherein the connector is removably connected to a connector receptacle in the ultrasound image processing apparatus, and the control means is further configured to perform control so that, by an instruction operation of the freeze switch, transmission by at least the second ultrasound transducer is stopped and an ultrasound image obtained by the second ultrasound transducer corresponding to the stopping is displayed as a still image, and all of the periods of transmitting and receiving are used as periods of transmitting and receiving by the first ultrasound transducer and ultrasound images obtained only by transmitting and receiving by the first ultrasound transducer are displayed as moving images.