An illumination device (101, 101a) configured to draw a predetermined pattern and installed in a vehicle body, comprising: a left headlight unit configured to be disposed at a front portion of the vehicle body on a left side and include a first drawing unit (14L, 20L) configured to irradiate light having a first drawing pattern (LFPA1, LFPA2) having a part of the predetermined pattern on a road surface in front of the vehicle body; a right headlight unit configured to be disposed at a front portion of the vehicle body on a right side and include a second drawing unit (14R, 20R) configured to irradiate light having a second drawing pattern (RFPA1, RFPA2) having another part of the predetermined pattern on the road surface and an irradiation-direction adjustment unit (34, 40) configured to shift positions of the irradiated drawing patterns (LFPA1, LFPA2, RFPA1, RFPA2) by the first and second drawing units (14L, 20L, 14R, 20R), wherein the first drawing pattern (LFPA1, LFPA2) includes a first auxiliary pattern (LFPO1, LFPO2) which is smaller than the part of the predetermined pattern, and the second drawing pattern (RFPA1, RFPA2) is different from the first drawing pattern and includes a second auxiliary pattern (RFPO1, RFPO2) which is smaller than the another part of the predetermined pattern, the irradiation-direction adjustment unit (34, 40) is configured to move the positions of the irradiated drawing patterns (LFPA1, LFPA2, RFPA1, RFPA2) of the first drawing unit (14L, 20L) and the second drawing unit (14R, 20R) so that the first auxiliary pattern (LFPO1) and the second auxiliary pattern (RFPO1) are shifted to coincide with each other or be located with a predetermined positional relationship to combine the first drawing pattern (LFPA1, LFPA2) and the second drawing pattern (RFPA1, RFPA2) into the predetermined pattern, and characterized in that the predetermined pattern formed by combining the first drawing pattern (LFPA1, LFPA2) and the second drawing pattern (RFPA1, RFPA2) is a combination of a width pattern (LFPA1) corresponding to a width of the vehicle body and a length pattern (RFPA1) having a length longer than the width pattern (LFPA1) and showing a length direction of the vehicle body. a left headlight unit configured to be disposed at a front portion of the vehicle body on a left side and include a first drawing unit (14L, 20L) configured to irradiate light having a first drawing pattern (LFPA1, LFPA2) having a part of the predetermined pattern on a road surface in front of the vehicle body; a right headlight unit configured to be disposed at a front portion of the vehicle body on a right side and include a second drawing unit (14R, 20R) configured to irradiate light having a second drawing pattern (RFPA1, RFPA2) having another part of the predetermined pattern on the road surface and an irradiation-direction adjustment unit (34, 40) configured to shift positions of the irradiated drawing patterns (LFPA1, LFPA2, RFPA1, RFPA2) by the first and second drawing units (14L, 20L, 14R, 20R), wherein the first drawing pattern (LFPA1, LFPA2) includes a first auxiliary pattern (LFPO1, LFPO2) which is smaller than the part of the predetermined pattern, and the second drawing pattern (RFPA1, RFPA2) is different from the first drawing pattern and includes a second auxiliary pattern (RFPO1, RFPO2) which is smaller than the another part of the predetermined pattern, the irradiation-direction adjustment unit (34, 40) is configured to move the positions of the irradiated drawing patterns (LFPA1, LFPA2, RFPA1, RFPA2) of the first drawing unit (14L, 20L) and the second drawing unit (14R, 20R) so that the first auxiliary pattern (LFPO1) and the second auxiliary pattern (RFPO1) are shifted to coincide with each other or be located with a predetermined positional relationship to combine the first drawing pattern (LFPA1, LFPA2) and the second drawing pattern (RFPA1, RFPA2) into the predetermined pattern, and characterized in that the predetermined pattern formed by combining the first drawing pattern (LFPA1, LFPA2) and the second drawing pattern (RFPA1, RFPA2) is a combination of a width pattern (LFPA1) corresponding to a width of the vehicle body and a length pattern (RFPA1) having a length longer than the width pattern (LFPA1) and showing a length direction of the vehicle body.