A laser radar comprising a light scanning type object detecting device, said light scanning type object detecting device comprising: a polygon mirror unit in which a first mirror surface and a second mirror surface are formed so as to inclined in respective directions intersecting with a rotation axis and to face each other with a predetermined angle; a light source; and a light receiving element, wherein the light scanning type object detecting device is configured such that a light flux emitted from the light source is reflected on the first mirror surface, thereafter, reflected on the second mirror surface, and projected so as to scan by rotation of the polygon mirror unit, and among the light flux projected so as to scan, a part of the light flux scattered on an object is reflected on the second mirror surface, thereafter, reflected on the first mirror surface, and received by the light receiving element, wherein in the polygon mirror unit, a part of each of the first mirror surface and the second mirror surface that exceeds a predetermined distance from the rotation axis in a direction orthogonal to the rotation axis, is cut out, and that H represents a distance in a direction of the rotation axis between an intersection point of extension lines of lateral sides of the first mirror surface and a first point on the first mirror surface that is most separated from the intersection point in the direction of the rotation axis; r represents a radius of a circle in a case where an area of a region of a received light flux received by the light receiving element when the received light flux positioned to confront the first mirror surface is viewed from a direction orthogonal to the optical axis, is converted into the circle; h represents a distance in the direction of the rotation axis between the first point and a gravity center of a region of a received light flux when the received light flux positioned to confront the first mirror surface is viewed from the direction orthogonal to the optical axis; and H' represents a distance in the direction of the rotation axis between the first point and a second point on the first mirror surface that is most separated from the first point in the direction of the rotation axis, formulas and are satisfied. when r < 0.4H, 0.1 < h/H ≤ (H' - r)/H when r ≥ 0.4H, 0.2 < h/H ≤ (H' - r)/H; and wherein the polygon mirror unit includes a plurality of pairs of the first mirror surface and the second mirror surface, and an intersecting angle between the first mirror surface and the second mirror surface is different for each of the plurality of pairs. a polygon mirror unit in which a first mirror surface and a second mirror surface are formed so as to inclined in respective directions intersecting with a rotation axis and to face each other with a predetermined angle; a light source; and a light receiving element, wherein the light scanning type object detecting device is configured such that a light flux emitted from the light source is reflected on the first mirror surface, thereafter, reflected on the second mirror surface, and projected so as to scan by rotation of the polygon mirror unit, and among the light flux projected so as to scan, a part of the light flux scattered on an object is reflected on the second mirror surface, thereafter, reflected on the first mirror surface, and received by the light receiving element, wherein in the polygon mirror unit, a part of each of the first mirror surface and the second mirror surface that exceeds a predetermined distance from the rotation axis in a direction orthogonal to the rotation axis, is cut out, and that H represents a distance in a direction of the rotation axis between an intersection point of extension lines of lateral sides of the first mirror surface and a first point on the first mirror surface that is most separated from the intersection point in the direction of the rotation axis; r represents a radius of a circle in a case where an area of a region of a received light flux received by the light receiving element when the received light flux positioned to confront the first mirror surface is viewed from a direction orthogonal to the optical axis, is converted into the circle; h represents a distance in the direction of the rotation axis between the first point and a gravity center of a region of a received light flux when the received light flux positioned to confront the first mirror surface is viewed from the direction orthogonal to the optical axis; and H' represents a distance in the direction of the rotation axis between the first point and a second point on the first mirror surface that is most separated from the first point in the direction of the rotation axis, formulas and are satisfied. when r < 0.4H, 0.1 < h/H ≤ (H' - r)/H when r ≥ 0.4H, 0.2 < h/H ≤ (H' - r)/H; and wherein the polygon mirror unit includes a plurality of pairs of the first mirror surface and the second mirror surface, and an intersecting angle between the first mirror surface and the second mirror surface is different for each of the plurality of pairs.