A lighting device and a cooking appliance including a lighting device are disclosed herein. The lighting device may include a light source installed outside a cavity where a through hole is formed, the light source including a light emitting diode (LED), a light tube installed outside the cavity to be connected to the light source and receiving light emitted from the LED via a light incidence surface that diffuses the light in an area where the through hole is formed, a transmissive cover installed on the cavity to cover the through hole to transmit the light diffused in the light tube toward inside of the cavity, and a supporter installed outside the cavity to support the light source such that it is spaced apart from the cavity.