A continuously variable valve timing device is provided and includes a cam sprocket connected with a camshaft having a plurality of cams to rotate the camshaft and an electric variable valve timing mechanism connected with the cam sprocket, and driven by an electric motor. A chain cover protects the cam sprocket and a chain system from foreign substances and an electric variable valve timing mechanism cover protects the electric variable valve timing mechanism from foreign substances. A seal ring partitions an internal space between the electric variable valve timing mechanism and the electric variable valve timing mechanism cover. In addition, a pressure maintaining device is mounted within the electric variable valve timing mechanism cover to maintain pressure formed within the internal space of the electric variable valve timing mechanism cover at about atmospheric pressure.