Provided is a biomagnetism measurement device which is capable of accurately diagnosing the site of a disorder and can be easily and readily used. According to one embodiment of the present invention, this biomagnetism measurement device 1 comprises: a tube 10； an expansion part 11 which is positioned at a necessary region of the tube 10 and can expand as a result of supply of a gas； a magnetism sensor part 13 which is fixed to the inner wall of the expansion part 11 and detects a magnetic field external to the tube 10. Preferably, the tube 10 and the expansion part 11 are formed from the same material, and the wall thickness of the expansion part 11 is less than the wall thickness of the tube 10.
