To reduce the radiation of noises from a part constituting a resonator so as to provide a stable reducing effect by setting the rigidity of the part constituting the resonator of a cover higher than that of the other part of the cover in one provided in the resonator between the cover for covering an engine and a noise generation vibrator.

An engine cover 2 attached to an engine upper part is composed of an engine cover main body 3 and a resonator 4. This resonator 4 is set between a noise generation vibrator 5 and the engine cover main body 3, and it includes a vibration plate 7 connected by the noise generation vibrator 5 and a connecting mechanism 6, a low rigid part 8 in its periphery and an opening part 9, and for the connecting mechanism 6, a projection 6a is in contact with the noise generation vibrator 5 and a projection 6b is in contact with the vibration plate 7. In this case, a projection 111 is formed inside a part 110 constituting the resonator 4 of the engine cover main body 3. Thus, the rigidity of the part 110 constituting the resonator 4 of the engine cover main body 3 is increased and a vibration level is reduced.