Abstract: A transmission and reception control unit controls transmission of an ultrasonic wave toward a blood vessel and reception of a reflected wave. A setting unit sets a signal range including a signal part for tracking movement of blood vessel walls of the blood vessel due to pulsation, and a signal waveform template in the signal range, among received signals of the reflected waves obtained at a first timing. Then, a detection unit detects a second timing when a signal waveform of the signal part corresponding to the signal range among the received signals and the signal waveform template satisfy predetermined equivalent conditions. A tracking unit starts tracking at the second timing.