Rearview mirror device with a built-in camera

Mirror housing (2) includes concave part (2C) formed in an opening manner downwardly which is arranged in the vicinity of photographing window (2B) where lens (5B) of the camera main body part (5A) is faced, and capable of accommodating an illumination light source. For this reason, opening area of the photographing window (2B) is decreased. Also, the circumference of the photographing window (2B) is reinforced by the cross-sectional box type form of the concave part (2C). Especially a bulge part with circular curved section is formed so that the lens of the camera main body part may rush in, to thereby decrease the opening area of the photographing window further.