PURPOSE: To switch light on the principle of operation as same as a reed switch by attaching an optical fiber to a lead piece as one body.

CONSTITUTION: Inverted V-shaped grooves 6 and 6' are provided on lower faces of reed pieces 2 and 2', and optical fibers 5 and 5' are introduced airtightly along these grooves from the outside of a glass tube 1. An interval (b) between contact parts 3 and 3' of lead pieces 2 and 2' is set to a non-conductive slippage length (a) or longer in the open state, and reed pieces 2 and 2' are provided with bending parts 7 and 7' so that end faces of optical fibers 5 and 5' coincide with each other in the close state, and the end part extending from the bending part 7' of one lead piece 2' is provided in a forked part. In this optical switch, when power supply to a coil 4 is cut off, contact parts 3 and 3' are opened, and end faces of optical fibers 5 and 5' are separated in the non-conduction slippage length (a) or longer distance from each other, and therefore, light is not transmitted. When power is supplied to the coil 4, reed pieces 2 and 2' are attracted to each other to close contact parts 3 and 3', and the end faces of optical fibers 5 and 5' coincide with each other, and thus, the switch is set in the conduction state.