Abstract: The present invention provides a slider wherein a Y-shaped guide groove which allows a fastener chain to pass therethrough is provided in a body of a slider, the intermediate partition which is raised inward on both sides of a guide post and extends from an inside end of the guide post toward a rear mouth is provided on an inner surface of one of upper and lower blades, and a top surface of the intermediate partition is formed into an entirely inclined slope such that a shoulder mouth side is higher than a rear mouth side, thereby enabling to catch and introduce coupling heads of fastener elements exposed from the side edges of the fastener tapes, so that the coupling heads of the right and left fastener elements are engaged with each other between the guide post and the rear mouth.