A lighting tool for a vehicle comprising: a light source; and a light guide body configured to guide light emitted from the light source, characterized in that the light guide body has: a first light guide portion disposed in front of the light source; a second light guide portion that is branched off from the first light guide portion and that extends so as to go around toward a side of the light source; an incidence portion that is located on a back surface side of the first light guide portion and that is configured to cause the light emitted from the light source to enter an inside of the first light guide portion; a side emitting portion that is located on a side of the first light guide portion facing the second light guide portion and that is configured to emit some of the light entered from the incidence portion toward the second light guide portion; a second emitting portion that is located on a front surface side of the first light guide portion and that is configured to emit some of the light (L, L3) entered from the incidence portion to an outside of the first light guide portion; and a concave portion that is located between the incidence portion of the first light guide portion and the second emitting portion and that forms an air layer, wherein the concave portion includes a light guide emission surface and a light guide incidence surface facing each other with the air layer being interposed therebetween in a direction of advance of the light entered from the incidence portion, and wherein among the light entered from the incidence portion, after emission from the light guide emission surface to the air layer, the light (L, L3) that entered an inside of the first light guide portion from the light guide incidence surface is emitted from the second emitting portion. a light source; and a light guide body configured to guide light emitted from the light source, characterized in that the light guide body has: a first light guide portion disposed in front of the light source; a second light guide portion that is branched off from the first light guide portion and that extends so as to go around toward a side of the light source; an incidence portion that is located on a back surface side of the first light guide portion and that is configured to cause the light emitted from the light source to enter an inside of the first light guide portion; a side emitting portion that is located on a side of the first light guide portion facing the second light guide portion and that is configured to emit some of the light entered from the incidence portion toward the second light guide portion; a second emitting portion that is located on a front surface side of the first light guide portion and that is configured to emit some of the light (L, L3) entered from the incidence portion to an outside of the first light guide portion; and a concave portion that is located between the incidence portion of the first light guide portion and the second emitting portion and that forms an air layer, wherein the concave portion includes a light guide emission surface and a light guide incidence surface facing each other with the air layer being interposed therebetween in a direction of advance of the light entered from the incidence portion, and wherein among the light entered from the incidence portion, after emission from the light guide emission surface to the air layer, the light (L, L3) that entered an inside of the first light guide portion from the light guide incidence surface is emitted from the second emitting portion.