A fluid driven oscillating piston motor is made up of a housing, a shaft mounted in the housing so that it may be oscillated, and a piston running out from the shaft for turning it. The piston divides a space in the housing into two working spaces that are alternately pressurized and relieved of pressure so that the piston is turned through an angle as limited by an adjustable system of stops. The housing is split up into a shell and a lid therefor. Inner faces of the shell engaged by the piston are free or joins because it is made by molding or pressure casting. The shell and the lid are held together by a band with a clamping effect. The piston is joined to the shaft by means of a bush with internal splines fitted into splines of the shaft. A piston seal placed round the shaft is molded in one piece on the oscillating piston.