A silencing member for an electrified vehicle, the member comprising a film type resonance structure which silences a sound generated from a sound source which is disposed in an electrified vehicle, the electrified vehicle being a vehicle that is driven by an electrified vehicle motor, the sound source being the electrified vehicle motor, wherein the sound source generates a narrow band sound, the film type resonance structure is disposed in the same space as the sound source or in a vehicle cabin of the electrified vehicle, the film type resonance structure includes at least one film-like member, a frame which supports the film-like member to allow vibration thereof, and a back plate which is installed in the frame to face the film-like member, the film-like member, the frame, and the back plate form a back space surrounded by the film-like member, the frame, and the back plate, the sound generated from the sound source is silenced by film vibration due to the film-like member of the film type resonance structure, in a case in which a wavelength of a peak frequency of the narrow band sound generated by the sound source is λ, a thickness of the back space is λ/6 or less in a direction perpendicular to a surface of the film-like member, characterized in that: a sound absorption coefficient of film vibration of the film-like member at a frequency in at least one high-order vibration mode is higher than a sound absorption coefficient at a frequency in a fundamental vibration mode, and a hardness of the film-like member, E × t 3 (Pa·m 3), is equal to or less than 21.6 × d -1.25 × Φ 4.15, where: E represents a Young's modulus of the film-like member in Pascals; t represents a thickness of the film-like member in meters; d represents a thickness of the back space in meters; and Φ represents a circle equivalent diameter of the region in which the film-like member vibrates, that is, the circle equivalent diameter of the opening portion of the frame in meters. wherein the sound source generates a narrow band sound, the film type resonance structure is disposed in the same space as the sound source or in a vehicle cabin of the electrified vehicle, the film type resonance structure includes at least one film-like member, a frame which supports the film-like member to allow vibration thereof, and a back plate which is installed in the frame to face the film-like member, the film-like member, the frame, and the back plate form a back space surrounded by the film-like member, the frame, and the back plate, the sound generated from the sound source is silenced by film vibration due to the film-like member of the film type resonance structure, in a case in which a wavelength of a peak frequency of the narrow band sound generated by the sound source is λ, a thickness of the back space is λ/6 or less in a direction perpendicular to a surface of the film-like member, characterized in that: a sound absorption coefficient of film vibration of the film-like member at a frequency in at least one high-order vibration mode is higher than a sound absorption coefficient at a frequency in a fundamental vibration mode, and a hardness of the film-like member, E × t 3 (Pa·m 3), is equal to or less than 21.6 × d -1.25 × Φ 4.15, where: E represents a Young's modulus of the film-like member in Pascals; t represents a thickness of the film-like member in meters; d represents a thickness of the back space in meters; and Φ represents a circle equivalent diameter of the region in which the film-like member vibrates, that is, the circle equivalent diameter of the opening portion of the frame in meters. a sound absorption coefficient of film vibration of the film-like member at a frequency in at least one high-order vibration mode is higher than a sound absorption coefficient at a frequency in a fundamental vibration mode, and a hardness of the film-like member, E × t 3 (Pa·m 3), is equal to or less than 21.6 × d -1.25 × Φ 4.15, where: E represents a Young's modulus of the film-like member in Pascals; t represents a thickness of the film-like member in meters; d represents a thickness of the back space in meters; and Φ represents a circle equivalent diameter of the region in which the film-like member vibrates, that is, the circle equivalent diameter of the opening portion of the frame in meters. E represents a Young's modulus of the film-like member in Pascals; t represents a thickness of the film-like member in meters; d represents a thickness of the back space in meters; and Φ represents a circle equivalent diameter of the region in which the film-like member vibrates, that is, the circle equivalent diameter of the opening portion of the frame in meters.