A multi-band antenna module is disposed in a housing of an electronic device. The housing has a grounding plane disposed therein and includes a metal frame part having two ends electrically connected to opposite side edges of the grounding plane. The multi-band antenna module includes a conductor, a substrate, a grounding section, and a first radiator section. The conductor is to be coupled across the metal frame part and the grounding plane so as to cooperate with the grounding plane and a portion of the metal frame part to form a closed loop thereamong, in which the substrate is disposed. The first radiator section and the grounding section are disposed on the substrate, with the grounding section to be coupled electrically to the grounding plane. A portion of the first radiator section is disposed to cooperate with the closed loop to resonate in a first frequency band. Another portion of the first radiator section is disposed to cooperate with the grounding section to resonate in a second frequency band.