Side turn signal lamp

A side turn signal lamp (20, 20A) includes a light guide member (40) having a light guide lens (42) and a plurality of LEDs (32a, 32c). The light guide lens (42) includes a front surface (42a) and a light entry end face (43a, 43c). The light guide lens (42) includes a front surface (42a) and a light entry end face (43a, 43c). The front surface (42a) is configured to correspond to a laterally extending opening (12) in an outer side wall (11) of a side mirror housing (10) so as to guide the light through the opening (12). The light guide lens (42) is configured to have a width that corresponds to the opening (12) having a shape of a slit in a front view and such that the light entry end face (43a, 43c) extends in a front-rear direction (X) of the side turn signal lamp (20, 20A). The LEDs (32a, 32c) are arranged in the front-rear direction (X) to directly face the light entry end face (43a, 43c).