REAR-VIEW MIRROR DEVICE MOUNTED IN A VEHICLE, VEHICLE-MOUNTED DISPLAY DEVICE, VEHICLE-MOUNTED DISPLAY SYSTEM

A vehicle-mounted display device includes a glass plate that includes a first arcuate surface at a first outer circumferential edge part, the first arcuate surface facing a front surface side, a casing that supports the glass plate from a rear surface side, the casing including a housing and a frame that projects from the housing, and a display unit stored in the casing configured to output a display light toward the glass plate. A rear surface of the glass plate and a front surface of the frame face each other at a spaced distance. The frame further includes a projection that projects, within the spaced distance, from the front surface of the frame toward the rear surface of the glass plate at a second outer circumferential edge part of the front surface of the frame, and the projection includes a second arcuate surface.