A light source unit, comprising: a first light-emitting element and a second light-emitting element; a rod lens including a first end surface, light emitted from the first and second light-emitting elements being incident on the first end surface, a second end surface positioned at a side opposite to the first end surface, and a side surface positioned between the first end surface and the second end surface; and a light-shielding body separated from the side surface, the light-shielding body covering the side surface, the light-shielding body including an opening that exposes at least a portion of the second end surface, characterised in a surface area of the second end surface being less than a surface area of the first end surface, the light-shielding body including a tip that protrudes further than the second end surface in a first direction, the first direction being from the first end surface toward the second end surface, a first plane crossing the first direction and being positioned at a same position as the tip in the first direction, a second plane crossing the first direction and being positioned at a same position as the second end surface in the first direction or between the tip and the second end surface, and a first surface area of the opening at the first plane being greater than a second surface area of the opening at the second plane. a first light-emitting element and a second light-emitting element; a rod lens including a first end surface, light emitted from the first and second light-emitting elements being incident on the first end surface, a second end surface positioned at a side opposite to the first end surface, and a side surface positioned between the first end surface and the second end surface; and a first end surface, light emitted from the first and second light-emitting elements being incident on the first end surface, a second end surface positioned at a side opposite to the first end surface, and a side surface positioned between the first end surface and the second end surface; and a light-shielding body separated from the side surface, the light-shielding body covering the side surface, the light-shielding body including an opening that exposes at least a portion of the second end surface, characterised in a surface area of the second end surface being less than a surface area of the first end surface, the light-shielding body including a tip that protrudes further than the second end surface in a first direction, the first direction being from the first end surface toward the second end surface, a first plane crossing the first direction and being positioned at a same position as the tip in the first direction, a second plane crossing the first direction and being positioned at a same position as the second end surface in the first direction or between the tip and the second end surface, and a first surface area of the opening at the first plane being greater than a second surface area of the opening at the second plane. the first direction being from the first end surface toward the second end surface, a first plane crossing the first direction and being positioned at a same position as the tip in the first direction, a second plane crossing the first direction and being positioned at a same position as the second end surface in the first direction or between the tip and the second end surface, and a first surface area of the opening at the first plane being greater than a second surface area of the opening at the second plane.