To provide a reflection type optical sensor type optical barrier device which obtains safe information and has a wide supervisory area.

A semiconductor galvano mirror 4 reflects laser beams from a laser diode 1 and scans a supervisory area 7. The mirror 4 reflects reflected light from an area that includes the area 7 and a light receiver 3 receives the light. A normal operation confirming means 12 extracts a pulse made by reflected light from reflectors 6 and 8 from an output i of the receiver 3 based on the pulse of a pulse generating means 10, confirms a normal operation according to the existence of the pulse and outputs '1' as an output e. An absence deciding means 11 eliminates the pulse reflected by the reflectors 6 and 8 from the output i of the receiver 3 based on the pulse of the means 10, extracts only a pulse generated by reflected light of a person, etc., decides as absence when the pulse does not exist and outputs '1' as an output g. An AND gate 13 outputs safe information '1' according to the output g=1 and the output e=1.