The utility model relates to a car door opening device for a car. The car door opening device comprises a starter device arranged on a car door or a car door frame, a buffer arranged on the car door frame or the car door, a car door sensor arranged on the car for detecting car door position and car door movement state, and a controller for receiving data of car door position and car door movement from the car door sensor and activating the starter device when the car is in a stop state. The controller instructs the starter device to repel the buffer to assist a user to open the car door or attract the buffer to assist the use to close the car door during closing process.