To provide a low cost grooved pin of a simple construction and an accurate alignment property.

This pin has plural strip grooves 10 comprised of top parts 11 and valley parts 12 formed, and a diameter of a locus circle connecting ridge lines of the top parts 11 is larger than that of a shaft part 2 and a diameter of a locus circle connecting bottoms of the valley parts 12 is smaller than that of a shaft part 2. The pin has a guide groove 20 longer than the strip groove 10 formed on a position equally dividing the shaft part 2 having plural strip grooves formed, and has guide peaks 21 larger than the locus circle connecting the ridge lines of the top parts 11 on both sides of the guide groove 20, and a diameter of a circle connecting a bottom part of the guide groove 20 is smaller than that of the shaft part 2. When the pin is pressed into a press in hole, the pin hardly inclines and it is easy to align the centers of the pin and the press in hole. The pin is surely pressed into the press in hole by a certain amount and the pin does not lift. As the pin is not pressed in under an inclined condition, an excessive press in force is not applied on parts to reduce damages of parts.