To obtain a user-friendly, excellent lighting controller allowing dim ming setting according to operating environment on site.

This heat ray sensing type automatic switch comprises a master device A and a slave device B respectively having heat ray sensors 17, 37 for detecting heat rays, connected to each other through a signal line S. The master device A has a switch element inserted in a power supply line to a lighting load L, and a signal processing part for turning the switch element on and off according to the presence and absence of a human body on the basis of output of the respective heat ray sensors 17, 37. The slave device B has a transmitting/receiving circuit part 31 for transmitting a signal for controlling the lighting load according to the presence and absence of the human body on the basis of the output of its own heat ray sensor 37 to the master device A through the signal line S. The master device A has a slide-type or volume- type knob 19 for setting a prescribed dimming level, while the signal processing part outputs a trigger signal according to the prescribed dimming level set by the slide-type or volume-type knob 19 to the switch element when turning the switch element on and off.