An engine that may be provided with a variable valve device may include an hydraulic pressure lash adjuster pivotally supporting one side of a swing arm, a valve supporting the other side of the swing arm, and an operating portion pushing a portion of the swing arm downwards so as to pivotally move the valve based on the hydraulic pressure lash adjuster, wherein the hydraulic pressure lash adjuster includes a housing in which an insertion hole may be formed therein, a slave piston that may be slidably inserted into the insertion hole, a master piston of which an end thereof may be placed into the insertion hole with a predetermined gap from the slave piston, wherein the other end of the master piston protrudes out of the housing and may be engaged with the one side of the swing arm, and an oil control valve that opens or closes a passage communicating with a master chamber that may be formed between the master piston and the slave piston in the housing.