A reed switch 10 includes a cylindrical glass tube 30 and a plurality of reeds 20 fixed to the glass tube 30 in a state where an end side including a contact point portion 22 of each of the reeds 20 is inserted in the glass tube 30. The reeds 20 are each produced by forming, by plastic working, a contact point portion 22 on an end side of a wire for a reed switch. The wire for a reed switch is composed of an iron-group alloy containing, by percent by mass, 1% or more and 10% or less of Fe, 10% or more and 35% or less of Ni, and the balance being Co and impurities and having a cubic crystal structure. The wire has a Curie temperature of 900°C or higher and a wire diameter of 1 mm or less. The wire is composed of a ternary alloy having a particular composition. Therefore, the wire has a high Curie temperature, a low resistance, and a particular structure and thus has good workability.