A positive crankcase ventilation (PCV) valve installation structure for installing a PCV valve of an engine on an engine body includes: a blow-by gas recirculation system that includes a ventilation hose that connects the engine body to an intake device introducing outside air into the engine body and that has a recirculation passage recirculating blow-by gas arising in the engine body to the intake device and an oil cooler device that exchanges heat between lubricating oil and a medium solution that is lower in temperature than the lubricating oil; and a cover that transfers heat of the oil cooler device to the PCV valve.