For the purpose of easily positioning a surface mount LED 1 at the time of soldering without impairing a heat dissipation function, an LED mounting board is adapted such that at least one pad 2 (hereinafter referred to as an "irregularly-shaped pad 2") other than a pad 3 having the highest heat dissipation function forms a shape different from the shape of a terminal 13 corresponding to the one pad, and the LED mounting board has an unpolymerized part where in a proper position where the LED 1 is to be mounted, the terminal 13 corresponding to the irregularly-shaped pad 2 and the irregularly-shaped pad 2 do not overlap, in which the unpolymerized part is provided such that only in the proper position where the LED is to be mounted, a resultant force of forces acting on the boundaries of parts where the pads 2, 3, and 4, and the terminals 13, 14, and 15 are respectively polymerized is balanced due to the surface tension of molten solder.