shown in fig1 the frame 1 substantially comprises a bed 8 a cantilever support 7 provided vertically on the bed b an arm 6 and an arm 6 cantilevered from the cantilever support 7 above the bed 8 the bed 8 the cantilever support 7 and the arm 6 are integrally formed of a synthetic resin in a substantially c shape the frame 1 supports a stitch forming mechanism including a loop taker and a mechanism for driving a needle 16 reciprocally up and down and constitutes a shell of the sewing machine in other words the frame 1 does not need any metallic frame for mounting the stitch forming mechanism accordingly it is possible to manufacture a lighter frame 1 having simplified structure compared with a conventional metal frame to mount a stitch forming mechanism covering with a resin cover the frame 1 may be formed of a synthetic resin material by using a well known injection molding method the synthetic resin material for the frame 1 may be a noncrystalline thermoplastic resin such as a styrene resin more specifically the material may be one or mixture of acrylonitrile butadiene styrene copolymer polystyrene acrylonitrile styrene acrylonitrile acrylate styrene acrylonitrile ethylene styrene chlorinated acrylonitrile polyethylene styrene of these materials a resinous matter having acrylonitrile butadiene styrene copolymer as the primary component with an inorganic additive of talc or glass bead has good rigidity and a good thermal expansion coefficient the usage of the above material may eliminate frame coating in the.