To provide a side surface light-emitting two-chip semiconductor light- emitting device, which can be miniaturized by reducing the size of a substrate.

This side surface light-emitting two-chip semiconductor light- emitting device 10 contains a substrate 12. Leads 18a and 18b are formed on one main surface 12a of the substrate 12, and leads 18c and 18d are formed on the other main surface. The leads 18a and 18c are connected on a side surface 12c of the substrate 12, and the leads 18b and 18d are formed, being stretched as far as the side surface 12c. Since bonding patterns are formed on both surfaces of the substrate 12, the size of the substrate can be reduced. LED chips 20a and 20b, which radiate different colors are bonded on both of the surfaces of the substrate 12. By applying a voltage to, at least one from among a part between an external connection electrodes 24a and 24b, and a part between an external connection electrodes 24a and 24c, different colors can be generated selectively, and a mixed color can be emitted.