An ignition plug cooling device of a vehicle engine for efficiently cooling the ignition plugs while increasing the freedom in the arrangement of the ignition plugs. A vehicle engine includes a first ignition plug and a second ignition plug for making respective electrodes thereof face a combustion chamber and are mounted on a cylinder head. An air flow passage through which a flow of air passes and a cooling oil chamber through which lubrication oil for the engine passes are formed in the cylinder head. The first ignition plug is arranged in the air flow passage to enable a cooling of the first ignition plug by the flow of air which passes through the air flow passage. The second ignition plug is arranged adjacent to the cooling oil chamber to enable a cooling of an area around the second ignition plug by oil which passes through the cooling oil chamber.