The instrument according to the present invention includes a band-like belt worn around a wrist, and a main body disposed at a portion of the belt corresponding to the volar surface or the dorsal surface of the wrist. An element for executing a blood pressure measuring function is mounted in the main body. A battery for supplying electric power to the element mounted in the main body is disposed at a portion of the belt located away from the main body in the circumferential direction around the wrist. A wire is provided in the belt, extends in the circumferential direction along the fluid bag, and electrically connects the element mounted in the main body and the battery. In the belt, the wire is disposed away from the fluid bag in the width direction perpendicular to the circumferential direction and extends along an edge section of the belt.
