A torque increase resonator for facilitating delivery of intake air to a combustion chamber of an engine by resonating with intake air pulsation generated by the delivery of intake air to the combustion chamber includes a chamber wall. The chamber wall projects in a surge tank of an intake manifold to define a resonance chamber. The resonance chamber is prevented from communicating with intake air. The chamber wall includes a resonating member, which is a thin film and resonates with the intake air pulsation. The chamber wall is integrally formed.