A probe includes a connector having a connection end surface, a first cover covering the connection end surface of the connector and defined by a surface perpendicular to a first direction corresponding to the direction toward which the probe is inserted, and a second cover configured to move in a second direction corresponding to a direction opposite to the first direction and which covers the connector by being stretched from the outer circumference of the first cover toward the second direction. The second cover moves in the second direction by receiving a press force directed toward the second direction from a wall surface formed by an opening of the adapter unit at the time of insertion of the connector into the adapter unit. The first cover is configured to be broken by the connectors press force directed in the first direction when the second cover moves in the second direction.
