A lamp unit comprising: an optical member; a base assembly disposed to be spaced a predetermined distance from the optical member with a space therebetween; a light source disposed on the base assembly; and a lens coupled to the base assembly to cover the light source; and wherein: the base assembly includes a heat sink and a substrate stacked on the heat sink, the lens includes at least two first protrusions and at least two second protrusions each of which protrudes from an edge of a lower surface of the lens toward the base assembly, said at least two first protrusions being symmetrically disposed with respect to a center of the lens, and said at least two second protrusions being symmetrically disposed with respect to the center of the lens, said at least two second protrusions are disposed to be spaced apart from said at least first protrusions, the substrate includes at least two first holes, each of said at least two first protrusions passing through each of said at least two first holes, the heat sink includes at least two second holes, each of said at least two second holes being aligned with each of said at least two first holes so that each of said at least two first protrusions pass therethrough, the lamp unit is characterized in that each of said at least two second protrusions does not penetrate the heat sink and passes through each of said at least two first holes, each of said at least two first protrusions includes a first contact surface to be in contact with the upper surface of the heat sink and a second contact surface to be in contact with the lower surface of the heat sink, and in that each of said at least two second protrusions includes a third contact surface formed as a lower end surface, the third contact surface passing through each of said at least two first holes to be contact with the upper surface of the heat sink. an optical member; a base assembly disposed to be spaced a predetermined distance from the optical member with a space therebetween; a light source disposed on the base assembly; and a lens coupled to the base assembly to cover the light source; and wherein: the base assembly includes a heat sink and a substrate stacked on the heat sink, the lens includes at least two first protrusions and at least two second protrusions each of which protrudes from an edge of a lower surface of the lens toward the base assembly, said at least two first protrusions being symmetrically disposed with respect to a center of the lens, and said at least two second protrusions being symmetrically disposed with respect to the center of the lens, said at least two second protrusions are disposed to be spaced apart from said at least first protrusions, the substrate includes at least two first holes, each of said at least two first protrusions passing through each of said at least two first holes, the heat sink includes at least two second holes, each of said at least two second holes being aligned with each of said at least two first holes so that each of said at least two first protrusions pass therethrough, the lamp unit is characterized in that each of said at least two second protrusions does not penetrate the heat sink and passes through each of said at least two first holes, each of said at least two first protrusions includes a first contact surface to be in contact with the upper surface of the heat sink and a second contact surface to be in contact with the lower surface of the heat sink, and in that each of said at least two second protrusions includes a third contact surface formed as a lower end surface, the third contact surface passing through each of said at least two first holes to be contact with the upper surface of the heat sink. the base assembly includes a heat sink and a substrate stacked on the heat sink, the lens includes at least two first protrusions and at least two second protrusions each of which protrudes from an edge of a lower surface of the lens toward the base assembly, said at least two first protrusions being symmetrically disposed with respect to a center of the lens, and said at least two second protrusions being symmetrically disposed with respect to the center of the lens, said at least two second protrusions are disposed to be spaced apart from said at least first protrusions, the substrate includes at least two first holes, each of said at least two first protrusions passing through each of said at least two first holes, the heat sink includes at least two second holes, each of said at least two second holes being aligned with each of said at least two first holes so that each of said at least two first protrusions pass therethrough, the lamp unit is characterized in that each of said at least two second protrusions does not penetrate the heat sink and passes through each of said at least two first holes, each of said at least two first protrusions includes a first contact surface to be in contact with the upper surface of the heat sink and a second contact surface to be in contact with the lower surface of the heat sink, and in that each of said at least two second protrusions includes a third contact surface formed as a lower end surface, the third contact surface passing through each of said at least two first holes to be contact with the upper surface of the heat sink.