Disclosed is a magnetoencephalography meter which includes a plurality of optical pumping magnetometers which are arranged in a helmet shape to cover the head of the subject. Each optical pumping magnetometer has a vapor cell which is filled with alkali metal atoms and is arranged substantially in parallel to the surface of the head of the subject, a laser light emission unit that emits laser light in a direction toward the head of the subject and causes laser light to enter the vapor cell, a reflection unit that reflects laser light passed through the vapor cell in a direction away from the head of the subject which is a direction substantially perpendicular to the surface of the head of the subject, and a polarization change detection unit that receives laser light reflected by the reflection unit and detects change in polarization of laser light.
