A blade mounting and dismounting jig is provided for mounting a blade on and dismounting a blade from a flange of a cutting apparatus which includes a boss, a blade mount for mounting the blade fitted thereover, the flange having an annular end face for supporting the blade thereon and being fixed to a distal end of a spindle, and a holder that cooperates with the flange in gripping and securing the blade in position. The blade mounting and dismounting jig includes a cylindrical jig body, a grip coupled to the jig body and having a diameter larger than the jig body, a plurality of first air ejection ports defined in a distal end portion of the jig body, a plurality of second air ejection ports defined in the jig body at a juncture between the jig body and the grip.