Oil pump for hermetic refrigerating compressor comprising a tubular sleeve having an upper portion affixed to at least one of the parts of crankshaft and rotor, and a lower portion having a lower end immersed in the lubricant oil, said tubular sleeve being provided with an inner surface presenting, along at least part of its longitudinal extension, at least one helical groove upwardly extending from the lower end; and a pump body disposed inside the tubular sleeve and defining, with the adjacent helical groove of the tubular sleeve, a lubricant oil ascending channel, said pump body presenting a lower end portion mounted to one of the parts of shell, cylinder block and stator, so as to be freely displaced within the tubular sleeve, in radial directions orthogonal to the crankshaft and rotatively locked in relation to the rotor.