A vehicular lamp comprising: a plurality of light source portions (17A, 17B); a circuit board; and a lighting circuit including a DC-DC converter configured to drive the plurality of light source portions (17A, 17B), wherein the DC-DC converter including a plurality of converter portions (2A, 2B), each of which includes a switching circuit portion (4A, 4B) and a control circuit portion (3A, 3B), the switching circuit portion (4A, 4B) being configured to obtain an output voltage by stepping up or stepping down an input voltage with a switching converter circuit including a switch element (T1, T51), a wound element (L1, L51), and a rectifier element (D1, D51), and the control circuit portion (3A, 3B) being configured to control the output voltage by controlling the switch element (T1, T51) of the switching circuit portion (4A, 4B), the DC-DC converter including as the plurality of converter portions (2A, 2B) a first converter portion including a first switching circuit portion and a first control circuit portion, and a second converter portion including a second switching circuit portion and a second control circuit portion, the vehicular lamp being characterized in that the plurality of converter portions (2A, 2B) are mounted on the circuit board; the first switching circuit portion, the first control circuit portion, the second control circuit portion, and the second switching circuit portion are arranged lined up in order of the first switching circuit portion, the first control circuit portion, the second control circuit portion, and the second switching circuit portion in one direction on the circuit board; and the first switching circuit portion and the second switching circuit portion are positioned at ends of the circuit board. a plurality of light source portions (17A, 17B); a circuit board; and a lighting circuit including a DC-DC converter configured to drive the plurality of light source portions (17A, 17B), wherein the DC-DC converter including a plurality of converter portions (2A, 2B), each of which includes a switching circuit portion (4A, 4B) and a control circuit portion (3A, 3B), the switching circuit portion (4A, 4B) being configured to obtain an output voltage by stepping up or stepping down an input voltage with a switching converter circuit including a switch element (T1, T51), a wound element (L1, L51), and a rectifier element (D1, D51), and the control circuit portion (3A, 3B) being configured to control the output voltage by controlling the switch element (T1, T51) of the switching circuit portion (4A, 4B), the DC-DC converter including as the plurality of converter portions (2A, 2B) a first converter portion including a first switching circuit portion and a first control circuit portion, and a second converter portion including a second switching circuit portion and a second control circuit portion, the vehicular lamp being characterized in that the plurality of converter portions (2A, 2B) are mounted on the circuit board; the first switching circuit portion, the first control circuit portion, the second control circuit portion, and the second switching circuit portion are arranged lined up in order of the first switching circuit portion, the first control circuit portion, the second control circuit portion, and the second switching circuit portion in one direction on the circuit board; and the first switching circuit portion and the second switching circuit portion are positioned at ends of the circuit board.