A wrist mechanism for an industrial robot comprising spline teeth (2A) formed in the outer circumference of a distal end of a curved driving shaft (2) provided on the inner side of an arm (1), spline grooves (2B) formed in the inner circumference of a first level gear (21) and in mesh engagement with the spline teeth (2A), spline teeth (3A) formed in the outer circumference of a distal end of a swivelling driving shaft (3), a hollow cylindrical intermediate shaft (30) having spline grooves (3B) formed in the inner circumference of an end thereof and in mesh engagement with the spline teeth (3A) and a second level gear (31) fixed to the outer circumference of the other end thereof, a bearing (301) for supporting an end of the intermediate shaft (30) on the inside of the first level gear (21) and bearings (22, 24) for supporting the other end of the intermediate shaft (30) on a fixed gear box (45).