A lamp for vehicles, comprising: a light source; a heat sink member; and a lens holder, wherein at the heat sink member and the lens holder, attachment structures to attach the lens holder to the heat sink member are respectively provided, characterized in that each of the attachment structures comprises: a surface attachment section which is provided at least at one of the heat sink member and the lens holder, and which has an insertion space section, the insertion space section being an attachment hole section; and an attachment hook section which is provided at a mounting plate section of at least the other one of the heat sink member and the lens holder to attach the lens holder to the heat sink member, and which is provided so as to have two faces corresponding respectively to a back face attachment section and an edge part of the attachment hole section, the back face attachment section being provided on one face of the edge part of the attachment hole section, opposite to another face thereof on which the surface attachment section is provided, the attachment hook section being configured such that, when being inserted, in an insertion direction, into the insertion space section of the corresponding attachment section and then is moved in a direction crossing the insertion direction, the attachment hook section and the mounting plate section at which the attachment hook section is provided, interpose the corresponding surface attachment section and the back face attachment section therebetween in the insertion direction and an opposite direction thereto by way of mutual abutment between the corresponding surface attachment section and the mounting plate section and mutual abutment between the back face attachment section and the attachment hook section. a light source; a heat sink member; and a lens holder, wherein at the heat sink member and the lens holder, attachment structures to attach the lens holder to the heat sink member are respectively provided, characterized in that each of the attachment structures comprises: a surface attachment section which is provided at least at one of the heat sink member and the lens holder, and which has an insertion space section, the insertion space section being an attachment hole section; and an attachment hook section which is provided at a mounting plate section of at least the other one of the heat sink member and the lens holder to attach the lens holder to the heat sink member, and which is provided so as to have two faces corresponding respectively to a back face attachment section and an edge part of the attachment hole section, the back face attachment section being provided on one face of the edge part of the attachment hole section, opposite to another face thereof on which the surface attachment section is provided, the attachment hook section being configured such that, when being inserted, in an insertion direction, into the insertion space section of the corresponding attachment section and then is moved in a direction crossing the insertion direction, the attachment hook section and the mounting plate section at which the attachment hook section is provided, interpose the corresponding surface attachment section and the back face attachment section therebetween in the insertion direction and an opposite direction thereto by way of mutual abutment between the corresponding surface attachment section and the mounting plate section and mutual abutment between the back face attachment section and the attachment hook section. a surface attachment section which is provided at least at one of the heat sink member and the lens holder, and which has an insertion space section, the insertion space section being an attachment hole section; and an attachment hook section which is provided at a mounting plate section of at least the other one of the heat sink member and the lens holder to attach the lens holder to the heat sink member, and which is provided so as to have two faces corresponding respectively to a back face attachment section and an edge part of the attachment hole section, the back face attachment section being provided on one face of the edge part of the attachment hole section, opposite to another face thereof on which the surface attachment section is provided, the attachment hook section being configured such that, when being inserted, in an insertion direction, into the insertion space section of the corresponding attachment section and then is moved in a direction crossing the insertion direction, the attachment hook section and the mounting plate section at which the attachment hook section is provided, interpose the corresponding surface attachment section and the back face attachment section therebetween in the insertion direction and an opposite direction thereto by way of mutual abutment between the corresponding surface attachment section and the mounting plate section and mutual abutment between the back face attachment section and the attachment hook section.