To provide post-attachment mechanism in which the post-attachment of an auxiliary light source and a light distribution accessory to an embedded lighting apparatus can be performed easily.

The post-attachment of an LED 16 is performed in steps in which firstly, an embedded lighting apparatus body 4 inserted into a fitting hole 3 of a ceiling surface 2 is taken out of the fitting hole 3, and a ring body 12 is positioned to match a position of the fitting hole 3, and the embedded lighting apparatus body 4 is inserted into a hole of the ring body 12 and the fitting hole 3, and the ring body 12 is pinched between a flange 7 and the ceiling surface 2 at the circumference of the fitting hole 3. As a result, for the post-attachment of the LED 16, a hole formed at the ceiling surface 2 is dispensed with and the after-fitting of the LED 16 can be performed without labor and cost.