A slider for a slide fastener useable with a slider with an automatic stop function to secure a tab to enable automatic engagement and prevent swinging of the tab, regardless of the type of tab, when the tab is tilted to an engaged portion side. An engaging portion is formed in an attachment hole of the tab. An engaged portion is formed in the slider body or the tab attachment part. When the tab is tilted to be almost parallel to an upper blade on the engaged portion side of the tab attachment part, due to a biasing force of the spring member, the lock pin moves the shaft portion of the tab downward and to an opposite side of a tilted direction, and a tip portion of the engaging portion of the tab is pulled into to be engaged with the engaged portion side of the tab attachment part.