A slider for a slide fastener (1, 2, 3), the slider comprising: a slider body part (10, 10a, 10b) including an upper wing plate, a lower wing plate that forms an element guide path with the upper wing plate, and a connection column that connects the upper wing plate with the lower wing plate; a stop tab body that is swingably held in the slider body part (10, 10a, 10b); and a tab elastic member that projects a part of the stop tab body into the element guide path by biasing the stop tab body, wherein a base part (20, 50, 70) formed integrally on the upper wing plate and an operation cover part (30, 60, 80) rotatably attached to the base part (20, 50, 70) are disposed; the operation cover part (30, 60, 80) includes a top plate part disposed opposite to an upper surface of the base part (20, 50, 70), and a pressing projecting part that projects from an inner surface of the top plate part and presses the stop tab body against a biasing force of the tab elastic member; the pressing projecting part has a structure in which by rotating the operation cover part (30, 60, 80), a locked state in which a part of the stop tab body is projected into the element guide path by biasing the stop tab body and an unlocked state in which the stop tab body is pressed by the pressing projecting part, whereby a part of the stop tab body is retreated from the element guide path can be switched therebetween; a cross section of the base part (20, 50, 70) orthogonal to a height direction is circular, the top plate part has a circular shape in a plan view of the slider, the slider being characterised in that a diameter of the top plate part is larger than a diameter of the base part (20, 50, 70), and is larger than the maximum longitudinal dimension of the lower wing plate, the slider body part (10, 10a, 10b) is covered in plan view by the operation cover part (30, 60, 80). a slider body part (10, 10a, 10b) including an upper wing plate, a lower wing plate that forms an element guide path with the upper wing plate, and a connection column that connects the upper wing plate with the lower wing plate; a stop tab body that is swingably held in the slider body part (10, 10a, 10b); and a tab elastic member that projects a part of the stop tab body into the element guide path by biasing the stop tab body, wherein a base part (20, 50, 70) formed integrally on the upper wing plate and an operation cover part (30, 60, 80) rotatably attached to the base part (20, 50, 70) are disposed; the operation cover part (30, 60, 80) includes a top plate part disposed opposite to an upper surface of the base part (20, 50, 70), and a pressing projecting part that projects from an inner surface of the top plate part and presses the stop tab body against a biasing force of the tab elastic member; the pressing projecting part has a structure in which by rotating the operation cover part (30, 60, 80), a locked state in which a part of the stop tab body is projected into the element guide path by biasing the stop tab body and an unlocked state in which the stop tab body is pressed by the pressing projecting part, whereby a part of the stop tab body is retreated from the element guide path can be switched therebetween; a cross section of the base part (20, 50, 70) orthogonal to a height direction is circular, the top plate part has a circular shape in a plan view of the slider, the slider being characterised in that a diameter of the top plate part is larger than a diameter of the base part (20, 50, 70), and is larger than the maximum longitudinal dimension of the lower wing plate, the slider body part (10, 10a, 10b) is covered in plan view by the operation cover part (30, 60, 80).