An MRI apparatus includes a transmitting coil which comprises an upper coil (5A) and a lower coil (5B) . With the objective of preventing variations in sensitivity even if samples to be inserted between the upper coil (5A) and the lower coil (5B) opposite to each other are different in body frame, a pre-scan is effected on a sample in a state in which the sample is placed in a space defined between the upper coil and the lower coil, and reflected waves sent from the coils are detected by a directional coupler (24). Further, a comparison controller (25-1) controls an attenuator (23) so that the voltages of the reflected waves are equalized. Afterwards, a main scan is carried out.
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