PURPOSE: To more precisely perform an SAR measurement by comparing a one obtained by converting an SAR upper limit value into an RF power value with the RF power value measured when the RF pulse of a pulse sequence is emitted in the state where a subject is placed to perform an alarm operation.

CONSTITUTION: The upper limit value of SAR is preliminarily inputted to a host computer 51 to provide a value RMSc converted into RMS value in a pulse sequence to be executed by the computer 51. Prior to the actual execution of a required pulse sequence to a subject, the RF pulse of the maximum power used in this pulse sequence is emitted at least once in the state where the subject is placed. The signal outputted from an RMS converter 64 at that time is inputted to a comparator 71, the value RMSd of the RMS is transmitted to a D/A converter 69 and converted into an analog signal, and the RMSd is compared with the RMSc by a comparator 71. When the RMSd exceeds the RMSc, an alarm is generated from an alarm generator 72.