Abstract: The present invention relates to a protective casing for a portable terminal with a built-in auxiliary battery, and the protective casing includes a casing body which covers and protects a side surface and a rear surface of a portable terminal, a battery mounting part positioned on a rear surface of the casing body to support installation and separation of the auxiliary battery, a battery power supply part which supplies power charged in the auxiliary battery to the portable terminal when the auxiliary battery is installed in the battery mounting part, a battery wireless charging part which receives wirelessly transmitted power and charges the auxiliary battery, and an additional component mounting part positioned on the rear surface of the casing body to support mounting of the battery wireless charging part.