Patent ID: 7683394

Claim:
An optical semiconductor device comprising: a base substrate which has a concave portion; a light-emitting element which is provided in the concave portion, and which emits light; a pair of lead parts which is provided to the base substrate, and which include lead frames for supplying power to the light-emitting element; a prevention member which is provided to the base substrate in a manner of being separated from the pair of lead parts and covering a whole side surface of the concave portion, and which prevents the light emitted by the light-emitting element from being incident upon the whole side surface of the concave portion; and a translucent member which is provided in the concave portion, and which seals the light-emitting element; wherein the prevention member includes: a cylinder part which has an inverted truncated cone shape, and is formed into a cylindrical shape; and a marginal part which horizontally extends from the cylinder part, wherein a part of the marginal part is embedded in the base substrate; wherein the marginal part includes a step part which is formed into a toric shape by bending the marginal part, and the step part is embedded in the base substrate.