A stimulation current value that causes the supramaximal stimulation according to a subject in the muscle relaxation state is detected. A muscle relaxation monitoring apparatus includes a calibration processing section 4 for performing a calibration process that electrically stimulates a nerve which is an observation portion of a subject, by a predetermined stimulation current value at a predetermined stimulation timing, and that acquires a stimulation current value of a supramaximal stimulation exceeding a maximal stimulation of the subject, based on an amplitude peak value of an electric signal that is based on a stimulation response of a muscle due to the electrical stimulation. The calibration processing section 4 performs, when the subject is in an awake state, the calibration process while using a first stimulation timing that is preset, as the stimulation timing, and performs, when the subject is in a muscle relaxation state, the calibration process while using a second stimulation timing that is longer in period than the first stimulation timing, as the stimulation timing.
MUSCLE RELAXATION MONITORING APPARATUS AND CALIBRATION PROCESSING METHOD