A slider for a slide fastener, the slider including: a slider body (10,10a) in which an upper blade and a lower blade are connected by a guide column, a tab provided with an attaching shaft portion at one end part, a stop pawl body (40, 40a) provided with a pawl base end portion (41, 46), an upper arm portion and a lower arm portion extending from the pawl base end portion (41, 46) and a pawl portion disposed at the lower arm portion, and a cover body (30, 30a) accommodating a part of the stop pawl body (40, 40a) in an inside and fixed in a cantilever state to the upper blade; in which the stop pawl body (40, 40a) is urged toward the upper blade; a tab insertion gap being able to pass the attaching shaft portion of the tab is provided between the upper blade and a free end portion of the cover body (30, 30a); the stop pawl body (40, 40a) is disposed such that the upper arm portion and the lower arm portion are disposed to be swingable up and down with respect to the slider body (10, 10a); the stop pawl body (40, 40a) protrudes the pawl portion to an element guide path formed between the upper blade and the lower blade by being urged toward the upper blade; being characterized in that: an open and close member (50, 50a) opening and closing the tab insertion gap is disposed alongside the stop pawl body (40, 40a) in a slider width direction, and is disposed so that a rear end part of the open and close member (50, 50a) is swingable up and down between a passing position at which the tab insertion gap is opened and the attaching shaft portion of the tab is passed, and a blocking position at which the attaching shaft portion is blocked not to be passed with respect to the slider body (10, 10a); and the open and close member (50, 50a) is urged toward the blocking position. a slider body (10,10a) in which an upper blade and a lower blade are connected by a guide column, a tab provided with an attaching shaft portion at one end part, a stop pawl body (40, 40a) provided with a pawl base end portion (41, 46), an upper arm portion and a lower arm portion extending from the pawl base end portion (41, 46) and a pawl portion disposed at the lower arm portion, and a cover body (30, 30a) accommodating a part of the stop pawl body (40, 40a) in an inside and fixed in a cantilever state to the upper blade; in which the stop pawl body (40, 40a) is urged toward the upper blade; a tab insertion gap being able to pass the attaching shaft portion of the tab is provided between the upper blade and a free end portion of the cover body (30, 30a); the stop pawl body (40, 40a) is disposed such that the upper arm portion and the lower arm portion are disposed to be swingable up and down with respect to the slider body (10, 10a); the stop pawl body (40, 40a) protrudes the pawl portion to an element guide path formed between the upper blade and the lower blade by being urged toward the upper blade; being characterized in that: an open and close member (50, 50a) opening and closing the tab insertion gap is disposed alongside the stop pawl body (40, 40a) in a slider width direction, and is disposed so that a rear end part of the open and close member (50, 50a) is swingable up and down between a passing position at which the tab insertion gap is opened and the attaching shaft portion of the tab is passed, and a blocking position at which the attaching shaft portion is blocked not to be passed with respect to the slider body (10, 10a); and the open and close member (50, 50a) is urged toward the blocking position. an open and close member (50, 50a) opening and closing the tab insertion gap is disposed alongside the stop pawl body (40, 40a) in a slider width direction, and is disposed so that a rear end part of the open and close member (50, 50a) is swingable up and down between a passing position at which the tab insertion gap is opened and the attaching shaft portion of the tab is passed, and a blocking position at which the attaching shaft portion is blocked not to be passed with respect to the slider body (10, 10a); and the open and close member (50, 50a) is urged toward the blocking position.