[TASK] To enable simultaneous formation of a diagonal cut-off line and a horizontal cut-off line in a vehicular illumination lamp that emits light from a light-emitting element forward using a translucent member disposed in front of the light-emitting element. [MEANS OF SOLVING THE PROBLEM] Light from a light-emitting element is internally reflected on a front surface 14a of a translucent member 14. The light is subsequently internally reflected again on a rear surface 14b of the translucent member 14, and then emitted from the front surface 14a. In this case, a light-emitting surface 12A of the light-emitting element 12 is disposed such that a lower end edge 12A1 is positioned on a horizontal line orthogonal to an optical axis Ax, thereby enabling formation of a horizontal cut-off line. Furthermore, in first and second zones Z1, Z2 respectively positioned diagonally upward on the oncoming vehicle lane side and diagonally downward on the host vehicle lane side, inner peripheral zones Z1i, Z2i are positioned more toward the inner peripheral side than first and second curves C1, C2, which are formed so as to project toward the optical axis Ax when viewed from the lamp front, and configured as zones for forming a diagonal cut-off line.