To provide a pulley type valve timing adjustment device capable of lessening product weight and restraining deterioration of a timing belt by preventing oil leakage.

Product weight of the pulley type valve timing adjustment device can be lessened since a pulley integrated housing 11 is formed by resin-molding a pulley 12 by inserting an aluminum housing 13. Further, the number of components and manufacturing cost can be reduced since the pulley integrated housing 11 as one component has a function for housing a vane rotor 9, and a function for rotating together with a crankshaft by connecting the timing belt 95. Furthermore, oil leakage to the outside can be prevented since a rear plate 4 is manufactured by cutting a steel material as a solid material and an O-ring 6 is oiltightly inserted on an interface between the housing 13 and the rear plate 4.