To provide a limit switch capable of precluding wasteful use of time and labor for performing the adjusting operation for limit switch and eliminating such inconvenience as out of actuation or failure originating from secular deterioration.

A switch body 41 is mounted on a jack outer while a contact shoe 42 is installed on a jack inner through a dog 43, and grounding of the jack inner is sensed by separating or contacting the switch body from/to the contact shoe in association with the grounding or out of grounding of the jack inner. The contact shoe is furnished with an energizing spring 45 so that the energizing force directed for the shoe to make contact with the contact 41b of the switch body is changed depending upon grounding or off-grounding of the jack inner. This energizing force of sprng is increased so that the shoe contacts with the contact of the switch body and intrudes when the jack inner is in the off-grounding condition and is decreased so that the shoe makes fine contacting with the contact and is not capable of being intrudes when the jack inner is in the grounded condition.