Keyless entry system

There is provided a keyless entry system with improved convenience, which can perform automatic locking of doors and automatic ventilation of inside of a vehicle. The keyless entry system comprises an onboard device 1, and a portable device 2 which performs radio communication with the onboard device 1. The onboard device 1 includes a door lock mechanism 12, a power window mechanism 13, and an ECU 16. The portable device 2 includes a memory 22 for storing setting information for closing mode and opening modes (first and second modes) of a window, and a mode selection switch 23 for selecting either the opening mode or closing mode and changing the setting information in the memory 22 according to the selected mode. On the basis of an answer signal b3 from the portable device 2, the ECU 16 automatically locks the door, drives the window and stops the window at its predetermined position based on the setting information stored in the memory 22.