To easily conduct a method for manufacturing a light body constituted by bonding: a light source; a light main body 3 in which the light source is assembled and a reflective surface reflecting the light emitted by the light source is formed; a lens part 4 transmitting the light emitted by the light source and abutted to the light main body 3; and an abutting part of the light main body 3 and the lens part 4, in a secondary injection molding process.

The method for manufacturing the light body comprises: a primary injection molding process which injection-molds the light main body 3 and the lens part 4 by injecting a resin between these die surfaces in the state that concavo-convex die surfaces 1a, 2a for forming inner and outer side faces of the light main body 3 and convexo-concave die surfaces 1b, 2b forming inner and outer side faces of the lens part 4 are abutted together; a reflective surface forming process in which a reflective surface 14 is vapor deposited on the inner side face of the concave surface 2c by housing the light main body 3 molded by a primary injection molding process in a vapor depositing device 5; and a secondary injection molding process for secondary-injection-molding to unite the light main body 3 and the lens part 4 in the state that the light main body 3 in which the reflective surface 14 is formed is abutted to the lens part 4.