PROBLEM TO BE SOLVED: To provide a light source part for operating light which uses an LED and can obtain an arbitrary irradiation pattern with respect to an object on the basis of an inexpensive structure.SOLUTION: A light source part 1 has: a cold mirror 2 which is provided with an attachment reception cylindrical part 3 at a central part of a parabolic reflection surface 2a an LED fixing member equipped with an attachment base part fixing an LED attachment surface on one surface and a heat radiation part 30 on the other surface and a pair of attachment pieces 14 protruding from an outer periphery part of the attachment base part toward one surface side and an LED support unit 11 which is equipped with an LED module that is fixed onto the LED attachment surface in close contact and mounts an LED, a slit plate provided with a slit of an arbitrary shape for passing LED light and fixed onto the LED attachment surface of the LED attachment member in close contact in the state that the LED module is covered, and an attachment cylindrical body part fixing the pair of attachment pieces 14 in the LED attachment member on a protrusion end side, attaches the attachment cylindrical body part to the attachment reception cylindrical part 3 of the cold mirror 2 attachably/removably, and oppositely disposes the LED on the reflection surface 2a.
