LIGHT EMITTING UNIT, AND LAMP DEVICE

Provided is a lamp device which can suppress the attenuation and reflection of a radar wave attributable to a light guide body, does not change an electromagnetic wave radiation pattern, and does not impair a radar function. The lamp device includes: a light guide body that covers at least a part of an electromagnetic wave radiation surface of a radar device; and a light source that supplies light to the light guide body, wherein, when the thickness of the light guide body is denoted by TG, and the wavelength of a radiated electromagnetic wave from the radar device in the light guide body is denoted by λd, TG is set such that TG < λd / 2 is satisfied when the reflection loss of the light guide body with respect to the radiated electromagnetic wave is below a transmission loss, and a reflection loss is -10 dB or less when the reflection loss is equal to or more than a transmission loss.