To provide a removable slotted pin which does not require time and labor of recovering the slotted pin removed from a fastening member and can be drawn out from the fastening member to be removed, and to provide a method for assembling and removing the slotted pin.

A removable slotted pin 11 includes: a bolt portion 2 provided with a head part 4, a shaft part 5 having a screw part 51, a connection part 6, and a top end part 7; and a substantially cylindrical pin portion 3 which covers an outer shape of the connection part 6 without coming in contact with the connection part 6, has an outer diameter larger than an outer diameter of the top end part 7 and opened from one end to the another end in a slit shape in such a longitudinal direction that an outer diameter and an inner diameter are reduced when being pressed into a hole 82 of the fastening member 8 in the longitudinal direction. Here, when the pin portion 3 is press-fitted into the hole 82 of the fastening member 8, one end is pressed against the shaft part 5 and, when the pin portion 3 is removed from the hole 82 of the fastening member 8, the another end is pressed against the top end part 7.