A transmission circuit for ultrasonic diagnosis includes a delay processing circuit that delays a transmission signal pattern and an operational circuit that calculates a delay time. A transmission timing for supplying the transmission signal pattern to a plurality of piezo electric elements corresponding to a plurality of channels is approximated by a multi-dimensional polynomial with locations of the plurality of piezo electric elements being variables so that the transmission timing becomes linear or arc-like. Coefficients in the multi-dimensional polynomial are supplied to the transmission circuit for ultrasonic diagnosis. The delay time in the delay processing circuit is determined by a first coefficient. The operational circuit calculates the delay time based on a second coefficient. The transmission signal pattern is supplied to the plurality of piezo electric elements at a transmission timing including the delay time according to the first coefficient and the delay time according to the second coefficient.