A novel two-dimensional optical signal processing circuit which becomes possible only by the introduction of a concave, flat or convex reflecting structure; and a method of producing the same. Disposed on an optical wave-guiding circuit board (50) formed with an output wave-guiding path (13) and an input wave-guiding path (14) are the optical axes of the input coupling end (I) and output coupling end (U) of a coupling circuit (15) such that the optical axes pass through the same point (Q) on a reflection structure (16), the reflection structure (16) being fabricated by using a laser ablation device (30).