The MRI device whose it is possible at brief to measure the B1 distribution of the RF transmission coil in high order accuracy, is offered. Because of that, image pickup means of the MRI device, time of flight from impression of the pre- impulse which is by RF lighting means and impression of aforementioned pre- impulse (TI) include with the multiple acquisition of signal sequences which differ and have the B1 distribution measurement sequence. The acquisition of signal sequence is run as the impulse whose huripu angle is small as a RF impulse is used, before longitudinal relaxation of after the pre- impulse ends. As for operation means, B1 distribution of RF lighting means is calculated making use of the graphics data where TI which is obtained respectively by the multiple acquisition of signal sequences, differs.短時間で高精度にRF送信コイルのB1分布を計測することが可能なMRI装置を提供する。そのために、MRI装置の撮像手段は、RF照射手段によるプリパルスの印加と、前記プリパルスの印加からの経過時間(TI)が異なる複数の信号取得シーケンスとを含みB1分布計測シーケンスを備える。信号取得シーケンスはRFパルスとしてフリプ角の小さいパルスを用いるとともに、プリパルス後の縦緩和が終わる前に実行される。演算手段は、複数の信号取得シーケンスにより、それぞれ得られたTIの異なる画像データを用いて、RF照射手段のB1分布を算出する。
