An illumination apparatus including an exciting light source, a reflective switching element, a first wavelength conversion element, and a second wavelength conversion element is provided. The exciting light source emits an exciting beam, and the reflective switching element is disposed on a transmission path of the exciting beam. When the reflective switching element is switched to a first state, the reflective switching element reflects the exciting beam to the first wavelength conversion element so as to excite the first wavelength conversion element to emit a first conversion beam. When the reflective switching element is switched to a second state, the reflective switching element reflects the exciting beam to the second wavelength conversion element so as to excite the second wavelength conversion element to emit a second conversion beam.