A transmissive image display device includes an image generation part configured to emit a light, and a light-guiding optical system configured to guide the light. The light-guiding optical system includes a first deflection part configured to deflect the light, and a second deflection part configured to further deflect the light deflected by the first deflection part to guide the light to a position of the exit pupil while transmitting a portion of external light, a first external light transmittance adjustment part is provided outside an optical path of the light between the first deflection part and the second deflection part, and an average external light transmittance of the first external light transmittance adjustment part is higher than one of an average external light transmittance of the first deflection part and an average external light transmittance of the second deflection part lower than the other.