A non-contact transmission device for an electronic lock includes a housing. The housing has an accommodation trough to accommodate a retainer in a slidable manner. The retainer is provided with an RFID coil. An inner side of the housing is formed with a positioning trough. When the retainer is slid in the accommodation trough, the RFID coil is positioned in the positioning trough, such that the RFID coil is closer to the outer edge of the housing without lowering the strength of the housing. When two non-contact transmission devices are mounted to a door frame and a door panel respectively, the distance between the RFID coils of the two non-contact transmission devices can be shortened to improve the transmission efficiency between the RFID coils.