PURPOSE: To obtain a better MR image of an object to be inspected with the optimization of a selection characteristic of a pre pulse by maximizing a generation time of the pre pulse in a range which in no way affects selective excitation timings of the pre-pulse and a data collection pulse.

CONSTITUTION: The timing of performing a selective excitation by a 90° RF pulse P1 as data collection pulse after done by a 180° pulse P0 as pre-pulse is determined by factors of a distance between a pre pulse plane and a data collection plane and a flow velocity of a fluid flowing into the data collection plane from the pre pulse plane. However, it is hard to forecast the flow velocity of the fluid accurately. So, a generation time of the pre pulse P0 is maximized in a range which in noway affects the selective excitation timing by the pulses to optimize a selection characteristic of the pre pulse, which makes the pre pulse plane approach the data collection plane as much as possible. This can prevent effects of uncertain flow velocity factors thereby enabling the obtaining of a better MR image of the object to be inspected.