A slider includes a slider body and a pull. The slider body includes an upper blade and a lower blade arranged to be spaced from each other in an up-down direction and to be parallel to each other, a guide post connecting the upper blade and the lower blade, and a pull attachment portion provided on an upper surface of the upper blade. The pull is attached to the pull attachment portion. A cut-out portion is formed on a front end portion of the upper blade at one of left and right sides with respect to the guide post. The cut-out portion is formed to be positioned at a rear side than a front end portion of the upper blade at the other of the left and right sides with respect to the guide post and than a front end portion of the lower blade.