A finger image acquisition apparatus comprising: a light guide that guides a light beam through a plurality of light reflective surfaces; and an image pickup unit that receives the light beam output from the light guide and captures a subject image, wherein the light guide comprises: a front surface including an input surface that receives a subject image; when a direction perpendicular to a front surface is defined as a direction of an x-axis, and two axes perpendicular to each other on a plane perpendicular to the x-axis are defined as a y-axis and a z-axis, respectively, a first light reflective surface that reflects light incident from the input surface along the x-axis to propagate the light along a direction of the y-axis; and a second light reflective surface that reflects the light reflected by the first light reflective surface to propagate the light along a direction of the z-axis, wherein the first and second light reflective surfaces form a part of an exterior surface of the light guide;wherein the first light reflective surface is parallel to the z-axis and crosses the x-axis, and the second light reflective surface is parallel to the x-axis and crosses the y-axis. a light guide that guides a light beam through a plurality of light reflective surfaces; and an image pickup unit that receives the light beam output from the light guide and captures a subject image, wherein the light guide comprises: a front surface including an input surface that receives a subject image; when a direction perpendicular to a front surface is defined as a direction of an x-axis, and two axes perpendicular to each other on a plane perpendicular to the x-axis are defined as a y-axis and a z-axis, respectively, a first light reflective surface that reflects light incident from the input surface along the x-axis to propagate the light along a direction of the y-axis; and a second light reflective surface that reflects the light reflected by the first light reflective surface to propagate the light along a direction of the z-axis, wherein the first and second light reflective surfaces form a part of an exterior surface of the light guide;wherein the first light reflective surface is parallel to the z-axis and crosses the x-axis, and the second light reflective surface is parallel to the x-axis and crosses the y-axis. a front surface including an input surface that receives a subject image; when a direction perpendicular to a front surface is defined as a direction of an x-axis, and two axes perpendicular to each other on a plane perpendicular to the x-axis are defined as a y-axis and a z-axis, respectively, a first light reflective surface that reflects light incident from the input surface along the x-axis to propagate the light along a direction of the y-axis; and a second light reflective surface that reflects the light reflected by the first light reflective surface to propagate the light along a direction of the z-axis, wherein the first and second light reflective surfaces form a part of an exterior surface of the light guide;wherein the first light reflective surface is parallel to the z-axis and crosses the x-axis, and the second light reflective surface is parallel to the x-axis and crosses the y-axis.