In an embodiment, a controller included in a blood flow measurement apparatus controls a scanner to iteratively scan one or more cross sections of an interested blood vessel. An image forming unit forms a phase image that represents chronological change in phase difference in the one or more cross sections based on data acquired through iterative scan. An image processor outputs a predetermined signal based on the chronological change in phase difference represented by the phase image. Upon receiving the predetermined signal, the controller controls the scanner to start scan for acquiring blood flow information on the interested blood vessel.
