A lamp for vehicles, comprising: a light source; a lens to emit light from the light source to an outside; a lens holder to hold the lens; and a mounting member to which the light source and the lens holder are mounted, wherein the lens is composed of: a lens section; and a flange section which is provided at a peripheral edge part of the lens section, the lens holder is composed of: a holding cylindrical section; and a holding edge part which is provided inside the cylindrical section from an end of the holding cylindrical section, and includes an opening section in which the lens section is disposed at a center part, and the lens and the lens holder are provided respectively with positioning sections to determine a position of the lens with respect to the lens holder in a reference optical axis direction of the lens, characterized in that the positioning sections provided to the lens holder each are composed of: a pressing section to press the lens by a pressing force caused by elastic restore of the pressing section in a direction of the reference optical axis direction; and a positioning surface arranged to be opposed to the pressing section to sandwich the positioning section provided to the lens between the pressing section and the positioning surface in the reference optical axis direction; and the positioning sections provided to the lens each are composed of: a receiving section arranged to form a shape of a protrusion section to receive the pressing force of the pressing section between the pressing section and the positioning surface; and a positioning abutment section arranged to form a shape of a protrusion section to abut against the positioning surface between the pressing section and the positioning surface by way of the pressing force that the receiving section receives, wherein the pressing section is provided on an inner circumferential face of the holding cylindrical section, the positioning surface is provided on an inner circumferential face of the holding edge part so as to oppose to the pressing section, the positioning abutment section is provided on a surface which opposes to the positioning surface, of the flange section, and the receiving section is provided on a surface which opposes to the pressing section, of the flange section, and in a range in which the pressing force of the pressing section is conveyed to the positioning abutment section. a light source; a lens to emit light from the light source to an outside; a lens holder to hold the lens; and a mounting member to which the light source and the lens holder are mounted, wherein the lens is composed of: a lens section; and a flange section which is provided at a peripheral edge part of the lens section, the lens holder is composed of: a holding cylindrical section; and a holding edge part which is provided inside the cylindrical section from an end of the holding cylindrical section, and includes an opening section in which the lens section is disposed at a center part, and the lens and the lens holder are provided respectively with positioning sections to determine a position of the lens with respect to the lens holder in a reference optical axis direction of the lens, a pressing section to press the lens by a pressing force caused by elastic restore of the pressing section in a direction of the reference optical axis direction; and a positioning surface arranged to be opposed to the pressing section to sandwich the positioning section provided to the lens between the pressing section and the positioning surface in the reference optical axis direction; and a receiving section arranged to form a shape of a protrusion section to receive the pressing force of the pressing section between the pressing section and the positioning surface; and a positioning abutment section arranged to form a shape of a protrusion section to abut against the positioning surface between the pressing section and the positioning surface by way of the pressing force that the receiving section receives, wherein the pressing section is provided on an inner circumferential face of the holding cylindrical section, the positioning surface is provided on an inner circumferential face of the holding edge part so as to oppose to the pressing section, the positioning abutment section is provided on a surface which opposes to the positioning surface, of the flange section, and the receiving section is provided on a surface which opposes to the pressing section, of the flange section, and in a range in which the pressing force of the pressing section is conveyed to the positioning abutment section.