A light source module comprising: a light source having an upper surface comprising a light emission surface; and a light-guide member comprising a lens portion having a rotation axis that extends through the light emission surface, wherein the lens portion comprises: a concave incidence surface facing the light emission surface of the light source and configured to receive light from the light source; a reflection surface disposed outside the incidence surface, the reflection surface being configured to reflect part of light entering through the incidence surface, and being inclined at an angle of 45 degrees or more from a direction perpendicular to the rotation axis; and an exit surface configured to allow part of the light entering through the incidence surface and light reflected by the reflection surface to exit the lens portion, and characterized in that the incidence surface comprises: a first incidence area having four-fold symmetry about the rotation axis and having a curved concave shape in a first cross section containing the rotation axis; and a second incidence area having a curved convex shape in a second cross section rotated 45 degrees with respect to the first cross section around the rotation axis and containing the rotation axis. a light source having an upper surface comprising a light emission surface; and a light-guide member comprising a lens portion having a rotation axis that extends through the light emission surface, wherein the lens portion comprises: a concave incidence surface facing the light emission surface of the light source and configured to receive light from the light source; a reflection surface disposed outside the incidence surface, the reflection surface being configured to reflect part of light entering through the incidence surface, and being inclined at an angle of 45 degrees or more from a direction perpendicular to the rotation axis; and an exit surface configured to allow part of the light entering through the incidence surface and light reflected by the reflection surface to exit the lens portion, and characterized in that the incidence surface comprises: a first incidence area having four-fold symmetry about the rotation axis and having a curved concave shape in a first cross section containing the rotation axis; and a second incidence area having a curved convex shape in a second cross section rotated 45 degrees with respect to the first cross section around the rotation axis and containing the rotation axis. a concave incidence surface facing the light emission surface of the light source and configured to receive light from the light source; a reflection surface disposed outside the incidence surface, the reflection surface being configured to reflect part of light entering through the incidence surface, and being inclined at an angle of 45 degrees or more from a direction perpendicular to the rotation axis; and an exit surface configured to allow part of the light entering through the incidence surface and light reflected by the reflection surface to exit the lens portion, and characterized in that the incidence surface comprises: a first incidence area having four-fold symmetry about the rotation axis and having a curved concave shape in a first cross section containing the rotation axis; and a second incidence area having a curved convex shape in a second cross section rotated 45 degrees with respect to the first cross section around the rotation axis and containing the rotation axis. a first incidence area having four-fold symmetry about the rotation axis and having a curved concave shape in a first cross section containing the rotation axis; and a second incidence area having a curved convex shape in a second cross section rotated 45 degrees with respect to the first cross section around the rotation axis and containing the rotation axis.