Silencing equipment provided with one or more flow channels through which cooling air flows has a flow channel forming member that forms the flow channel, and an acoustic absorbent member that is fixed to the flow channel forming member. A resonance type silencer is formed on a wall surface of the flow channel by providing a cavity for the resonance type silencer in the acoustic absorbent member and an aperture for the resonance type silencer in a portion of the flow channel forming member. The resonance type silencer sets a frequency of noise necessary to be reduced based on a peak frequency of noise generated by a fan. The silencing equipment further has a slide member which slides by a slide mechanism to adjust the area of the top of the aperture. The silencing equipment for electronic devices capable of cooling heat generating sections thereof with air has a small and simple structure and can improve a silencing effect by blowing air.