To provide a guide pin, in which the quantity of the guide pin projected can be adjusted by a simple structure.

The guide pin for the door is composed of a cylindrical case 1, in which an underside is opened, a stopper 2 being screwed into the lower section of the case 1 and having a through-hole 2a in an axial center section, a pin 3 inserted into the through-hole 2a under the state, in which the pin 3 can be slid vertically so as not to be slipped off to a lower section, and the state, in which a lower section is projected from the lower end of the stopper 2, and a spring 4 elastically pressing the pin 3 to a lower section at all times. A part of the lower section of the stopper 2 is exposed from the lower end of the case 1, a rotary operating section 2b is formed, and the quantity of the pin 3 projected can be adjusted by vertically moving the stopper 2 by rotating the rotary operating section 2b.