A sleeve flange type mounting device for mounting a grinding wheel on a spindle of a grinding machine consists of a sleeve flange defining a sleeve portion and a flange portion, a pressing plate fitted on the sleeve portion for clamping the grinding wheel on the flange portion, a cover fitted on the pressing plate, three balance weights received in a circular recess defined by the pressing plate and each having a first arc-shaped side abutting against a far wall near a circumferential periphery of the pressing plate and a second arc-shaped side abutting against a circumferential periphery of the cover, and a nut threadedly engaging an extremity of the sleeve portion and exerting a compressive force on the cover.