A power saving device includes a first power connector adapted for connecting to a power source, a second power connector adapted for connecting to a power wire of a display, an infrared sensor, an infrared coupling circuit, a wave shaping circuit, and a switch circuit connected between the first and second power connectors. The infrared sensor senses user status and initiates a user status signal. The wave shaping circuit receives the user status signal via the infrared coupling circuit and converts the user status signal to a voltage signal. The switch circuit receives the voltage signal and converts the voltage signal to a control signal to control the connection between the first power connector and the second power connector.