The invention provides a light guide member and an illuminating device which are able to efficiently uniformly irradiate illumination light to only an area requiring illumination. Therefore, a reflection face is constructed by reflection stripes such as many grooves, etc. widened in a concentric circle shape. Light from a light source unit is widened toward this entire reflection face without irregularities by a diffusing portion such as a reflection prism, etc. Thus, only the range actually requiring the illumination can be illuminated without irregularities, and visibility of the illumination range using a front light is raised.