A transmittance-variable device, comprising: a retardation film having in-plane retardation of 5,000 nm or more for light having a wavelength of 550nm; a liquid crystal alignment film; and a switchable liquid crystal layer configured to implement a twist orientation mode by means of the liquid crystal alignment film, wherein the retardation film, the liquid crystal alignment film and the liquid crystal layer are comprised in the above order, wherein a twist angle of the twist orientation mode is in a range of 50 degrees to 180 degrees, wherein the liquid crystal layer comprises a dichroic dye; the transmittance-variable device does not comprise a passive polarizing layer; the smaller one, A, of the two angles between the slow axis of the retardation film and the alignment direction of the liquid crystal alignment film satisfies Equation 1 below in a case where a product (Δnd) of a refractive index anisotropy (Δn) of the liquid crystal layer for light having a wavelength of 550 nm and a thickness (d) of the liquid crystal layer is 0.7 μm or less, and the smaller one, A, of the two angles between a slow axis of the retardation film and an alignment direction of the liquid crystal alignment film satisfies Equation 2 below in a case where a product (Δnd) of a refractive index anisotropy (Δn) of the liquid crystal layer for light having a wavelength of 550 nm and a thickness (d) of the liquid crystal layer is in a range between (0.7 - 2.0) μm: 0.05 × Δ nd × T / μ m + 10 ≤ A ≤ 0.16 × Δ nd × T / μ m + 60 wherein the Δn is a refractive index anisotropy of the liquid crystal layer for light having a wavelength of 550 nm, the d is a thickness (unit: μm) of the liquid crystal layer, and the T is the twist angle (unit: degree) of the twist orientation mode: 0.16 × Δ nd × T / μ m − 10 ≤ A ≤ 0.16 × Δ nd × T / μ m + 20 wherein, the Δn is the refractive index anisotropy of the liquid crystal layer for light having a wavelength of 550 nm, the d is the thickness (unit: μm) of the liquid crystal layer, and the T is the twist angle (unit: degree) of the twist orientation mode. a retardation film having in-plane retardation of 5,000 nm or more for light having a wavelength of 550nm; a liquid crystal alignment film; and a switchable liquid crystal layer configured to implement a twist orientation mode by means of the liquid crystal alignment film, wherein the retardation film, the liquid crystal alignment film and the liquid crystal layer are comprised in the above order, wherein a twist angle of the twist orientation mode is in a range of 50 degrees to 180 degrees, wherein the liquid crystal layer comprises a dichroic dye; the transmittance-variable device does not comprise a passive polarizing layer; the smaller one, A, of the two angles between the slow axis of the retardation film and the alignment direction of the liquid crystal alignment film satisfies Equation 1 below in a case where a product (Δnd) of a refractive index anisotropy (Δn) of the liquid crystal layer for light having a wavelength of 550 nm and a thickness (d) of the liquid crystal layer is 0.7 μm or less, and the smaller one, A, of the two angles between a slow axis of the retardation film and an alignment direction of the liquid crystal alignment film satisfies Equation 2 below in a case where a product (Δnd) of a refractive index anisotropy (Δn) of the liquid crystal layer for light having a wavelength of 550 nm and a thickness (d) of the liquid crystal layer is in a range between (0.7 - 2.0) μm: 0.05 × Δ nd × T / μ m + 10 ≤ A ≤ 0.16 × Δ nd × T / μ m + 60 wherein the Δn is a refractive index anisotropy of the liquid crystal layer for light having a wavelength of 550 nm, the d is a thickness (unit: μm) of the liquid crystal layer, and the T is the twist angle (unit: degree) of the twist orientation mode: 0.16 × Δ nd × T / μ m − 10 ≤ A ≤ 0.16 × Δ nd × T / μ m + 20 wherein, the Δn is the refractive index anisotropy of the liquid crystal layer for light having a wavelength of 550 nm, the d is the thickness (unit: μm) of the liquid crystal layer, and the T is the twist angle (unit: degree) of the twist orientation mode.