A door body holding structure that can hold a door body at an open position by using a simple configuration. A projecting portion 40, which projects toward a containing wall 38 side, is provided on an outer surface of a bearing portion 32 of a fixed-side hinge at a position facing the containing wall 38 where the projecting portion 40 does not come into contact with an inner surface of a guide portion 34 when the door body 18 is at a closed position but the projecting portion 40 comes into contact with the inner surface of the guide portion 34 when the door body 18 is at the open position. A separation dimension between a projecting end of the projecting portion 40 and the containing wall 38 is set to be smaller than a thickness dimension of the guide portion 34. That is, when the inner surface of the guide portion 34 reaches the position at which it comes into contact with the projecting portion 40 by pivoting movement of the door body 18 from the closed position toward the open position, the guide portion 34 is sandwiched and held between the projecting portion 40 and the containing wall 38, thereby holding the door body 18 at the open position.