According to one embodiment, an ultrasound diagnosis apparatus transmits ultrasound waves to a subject from a plurality of transducers each corresponding to one of a plurality of channels, and receives reflected waves generated in the subject by the transducers. The ultrasound diagnosis apparatus includes a control circuit and a receiving circuit. The control circuit controls channels used to transmit ultrasound waves and channels not used to transmit ultrasound waves among the channels. The receiving circuit receives the reflected waves, and includes a preamplifier and an impedance control circuit. The preamplifier amplifies the reflected waves. The impedance control circuit is located on the upstream side of the preamplifier, and sets line impedance in a transmitting period, in which the ultrasound waves are transmitted from the transducers to the inside of the subject, to be lower than that in a receiving period, in which the reflected waves are received by the transducers.
