A wabble plate type variable displacement compressor has a wabble plate rotation preventing mechanism including an inner ring axially movable relative to a main shaft, an outer ring connected to the wobble plate, a plurality of balls placed between guide grooves of the inner and outer rings and performing power transmission, and a sleeve axially movably engaged with the inner ring, provided so as to be axially movable together with the inner ring. A shape differs between the axial cross-sectional profiles of substantially concave spherical surfaces formed respectively in the inner periphery of the outer ring and the outer periphery of the sleeve such that the closer to the axial opposite ends of the contact portion between both the surfaces the position is, the greater the clearance between these surfaces. Implementation of the wabble plate rotation preventing mechanism in such a compressor can provide excellent durability and silent performance.