A lighting apparatus is provided that includes a magnetron configured to generate microwaves having a predetermined frequency, a waveguide including a first wave guide space configured to introduce and guide the microwaves and a second wave guide space expanded from the first wave guide space, a resonator to which the microwaves are transmitted from the waveguide and a bulb located in the resonator, the bulb encapsulating a light emitting material and being configured to emit light in response to the transmitted microwaves. The second wave guide space is located in a transmission path of the microwaves transmitted from the magnetron to the resonator.