In order to explore novel materials as half-metallic ferromagnets, CoX’MnZ (X’ = Pd and Ir, Z = Al, Si, Ga, and Ge) quaternary Heusler alloys containing 4d or 5d transition element were fabricated. Although all of CoPdMnZ alloys show phase separation in the microstructural observations for the present annealing condition, single phase is obtained in CoIrMnGa and CoIrMnGe for CoIrMnZ series. From the XRD experiments, it has been suggested that the Co and Ir atoms are disordered. The spontaneous magnetization for CoInMnGa evaluated from the magnetization curve measured at 6 K is 58.1 A m2/kg, and the value is converted to 3.9 μB/f.u. which almost closes to the expected value of 4 from the Slater-Pauling rule. The Curie temperature is decided to be 422 K from the thermomagnetization curve and DSC measurement.