To reduce the appearance of the shadow of a lighting equipment without greatly lowering illuminance in an internally lighted signboard in which a HID (high intensity discharge) lamp apparatus is arranged at the side end part.

The HID lamp apparatus 2 in which a HID lamp 2a is arranged at a reflection mirror 2b, is disposed at the base body parts 1a, 1b of the short side of a rectangular frame-shaped signboard base body part 1. Display signboard parts 3a, 3b made of a vinyl chloride sheet reinforced with a net-shaped reinforcing material, are provided all over the both surfaces formed of the frame-shaped signboard base body part. The incident angle of direct light emitted from the HID lamp 2a of the HID lamp apparatus to a shortest distance vicinity part of the display signboard part is set to 20° to 30° by adjusting louvers 2c, 2d provided inside and at the outer edge part of the reflection mirror of the HID lamp apparatus, to constitute the internally lighted signboard.