A detection apparatus includes a casing, a movable member moving from a position outside the casing to a position inside the casing upon contact of a detection object, a radio communication device disposed on the movable member and configured for radio communication with a sending and receiving unit via radio waves, a shielding member for shielding the radio communication between the radio communication device and the sending and receiving unit in a state that the movable member is located within the casing, and a controller for determining the presence of the detection object by determining whether the sending and receiving unit can communicate with the radio communication device.