To provide a magnetic resonance imaging apparatus capable of adjusting irradiation gain at a high speed without being affected by receiving sensitivity.SOLUTION: The magnetic resonance imaging apparatus includes: an imaging part including a transmission part for applying a high-frequency magnetic field pulse to a subject, and a receiving part for detecting a nuclear magnetic-resonance signal from the subject； an operation part for performing prescribed arithmetic processing including imaging processing to the nuclear magnetic-resonance signal acquired by the receiving part； and a control part for controlling imaging by the imaging part. The control part includes an imaging sequence of performing pre-scanning, prior to the imaging, according to a predetermined intensity of high-frequency magnetic field pulse. The operation part includes: a high-frequency magnetic field distribution acquisition part that acquires high-frequency magnetic field distribution generated by the predetermined intensity of high-frequency magnetic field pulse by the transmission part, on the basis of the nuclear magnetic-resonance signal detected by the receiving part in the pre-scanning； an average value calculation part for calculating an average value of the high-frequency magnetic field distribution； and an intensity adjustment part that adjusts the intensity of the high-frequency magnetic field pulse that the transmission part applies, on the basis of the average value.SELECTED DRAWING: Figure 1【課題】高速、かつ、受信感度の影響を受けずに照射ゲイン調整を行える磁気共鳴イメージング装置を提供する。【解決手段】磁気共鳴イメージング装置は、被検体に高周波磁場パルスを照射する送信部及び被検体からの核磁気共鳴信号を検出する受信部を有する撮像部と、受信部が取得した核磁気共鳴信号に対して画像化処理を含む所定の演算処理を行う演算部と、撮像部による撮像を制御する制御部とを備え、制御部が、本撮像に先立って、予め定めた強度の高周波磁場パルスに従ってプリスキャンを行う撮像シーケンスを有し、演算部が、プリスキャンにおいて受信部により検出した核磁気共鳴信号に基づいて、送信部による予め定めた強度の高周波磁場パルスによって発生した高周波磁場分布を取得する高周波磁場分布取得部と、高周波磁場分布の平均値を算出する平均値算出部と、平均値に基づいて送信部が照射する高周波磁場パルスの強度を調整する強度調整部とを備える。【選択図】図１
