To solve the problem of having a possibility of the lowering of combustion stability due to application of an excessive valve overlap by the lowering of changeover responsiveness of actuators 30 and 40 caused by the viscosity increase of an operating fluid when an engine is cold.

This variable valve system for an internal combustion engine has an operating angle change mechanism 10 for changing the operating angle of an intake valve 1; a phase change mechanism 20 for changing a phase; actuators 30 and 40 for driving the respective mechanisms 10 and 20 according to the supply pressure of the operating fluid; and a control part 50 for controlling the supply pressure to the actuators 30 and 40 through solenoid valves 31 and 41. When the engine is cold with the temperature of the operating fluid being lower than a specified temperature, the change amount of the change mechanisms 10 and 20 is limited so that the opening timing of the intake valve 1 is delayed in comparison with specified stable limit opening timing.