To provide a trunk width measuring unit capable of improving reliability of measurement precision, and a visceral fat measuring device. The trunk width measuring unit is provided with a first contact portion to be brought into contact with an upper surface of a trunk of a user in a supine position, a second contact portion to be brought into contact with one of side surfaces of the trunk, a third contact portion to be brought into contact with the other side surface of the trunk, and a trunk width calculating unit for calculating vertical width and horizontal width of the trunk from height from an upper surface of a bed to a contact position of the first contact portion and a distance between the second contact portion and the third contact portion.