SENSOR

PROBLEM TO BE SOLVED: To provide a sensor hardly causing uncoupling of a connector caused by contact with an external object. SOLUTION: A connector part has, inside of an upper part, a space (insertion space 56) for inserting a medium diameter part 20b and a small diameter part 20c of an external connector 20 having a stepped cylindrical shape. The outside of a circumferential wall 57 is covered with an external cylinder 8, and, on the prescribed positions of the circumferential wall 57 and the external cylinder 8, a pair of communicating holes 11 for communication both parts are formed. On the other hand, the external connector 20 is equipped with a pair of tongue- shaped abutting members 80 on right and left sides of the lower end of the medium diameter part 20b, and engaging projections 81 are formed on the tips of the members 80. When the medium diameter part 20b and the small diameter part 20c are inserted into the insertion space 56, the engaging projections 81 are engaged with the communicating holes 11 from the inside of the circumferential wall 57 of the connector part 10, to thereby fix the external connector 20 to the connector part 10.