An antenna mounting structure of an electronic device includes a casing and an antenna in the casing. The antenna includes a signal receiving portion and a first securing member connecting the signal receiving portion. The first securing member defines a through hole. The casing includes a first pin, a first catch near the first pin, and a first rib extending from the first pin. The first pin extends through the through hole of the first securing member of the antenna. The first rib supports the first securing member. The first catch fixedly clasps the first securing member on the first pin and the first rib.