An air-intake apparatus includes an inner pipe member and an outer pipe member. The inner pipe member defines an intake passage that connects an inlet and a surge tank. Air is drawn into the inlet. A diameter of the inner pipe member gradually increases when the inner pipe member extends toward a surge tank-side end portion of the inner pipe member. The outer pipe member covers an outer circumferential side of the inner pipe member and defines a resonator between the outer pipe member and the inner pipe member. The resonator communicates with the intake passage.