A rear glass according to the invention is for attachment to a lift-up backdoor that closes an opening in a rear portion of a vehicle, and includes a glass plate, a defogger disposed in a vicinity of a center of the glass plate in an up-down direction, and a shared antenna installed on the glass plate upward or downward of the defogger, the shared antenna including a power supply unit, an AM antenna connected to the power supply unit, and an FM antenna connected to the power supply unit, and a relationship between an element length L