An illumination apparatus includes a light source unit having solid light-emitting elements and a sensor unit having a wave transmission portion for transmitting energy waves of specified frequency and a wave reception portion for receiving the energy waves reflected from an object. The sensor unit outputs a detection signal by detecting the object within a detection range based on the difference in frequency between the transmitted and received energy waves. The illumination apparatus further includes a control unit responsive to the detection signal from the sensor unit for performing a control operation to turn on the light source unit, and a power source unit for supplying electric power to the light source unit. The power source unit is arranged outside the detection range of the sensor unit. The sensor unit is provided on the opposite side to the direction of light irradiated from the light source unit.