To solve the problem that a lot of general dust-proofed and waterproofed switch structures use a rubber sealing packing, and they secure the airtightness inside the switch as a sealed construction by using a rubber boot made of an elastic rubber, but when they are used in a machine processing site under a poor environment, cutting chips and so on are generated and make holes in the rubber boot and it may cause a trouble.

Dust-proof and waterproof function is strengthened in a sealed structure by surrounding a magnet and a hall IC with a metal case. It is used even in a machine processing site under a poor environment. Also, it is explosion-proofed because it is a non-contact type. This switch is used in a wide range by having such an excellent function.