Abstract: A soundproofing transformer includes a tank; a winding portion and a core portion provided inside the tank; an insulating fluid provided inside the tank; a reinforcing member provided outside of the tank; a cavity having a resonance space and connected to the reinforcing member by a coupling member; a partition member stacked on the cavity, and having an acoustic absorption portion; a noise inlet member having a first inlet facing the tank, connected to the resonance, and configured to transmit noise introduced from the first inlet to the resonance space; and a noise reduction panel connected to at least one of the partition member and the noise inlet member, and having a second inlet provided to communicate with the acoustic absorption portion while facing the tank.