Patent ID: 8355778

Claim:
A trunk width measuring unit, comprising: 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; a unit main body in which the first contact portion is attached movably in a vertical direction, the second contact portion and the third contact portion are attached movably in a horizontal direction, and the second contact portion or the third contact portion is placed at a position where the second contact portion or the third contact portion is brought into contact with the side surface of the trunk of the user; and a trunk width calculating unit for calculating vertical width and horizontal width of the trunk, the trunk width calculating unit calculating the height from a plane on which the user lies to a contact position of the first contact portion based on a distance between the second contact portion and the third contact portion, wherein the first contact portion is attached to the unit main body so as to be lowered by self-weight of the first contact portion and moved in the vertical direction relative to the unit main body in a state that the first contact portion is disposed on the upper surface of the trunk of the user, and the first contact portion is thus movable so as to follow a change in a shape of the trunk based on breathing of the user.