An eye gaze detection supporting device comprising: an illuminator including a light source that performs irradiation with light; a plurality of imaging units (202, 203); a position detector (351, 352) configured to detect a first position indicating a center of a pupil and a second position indicating a center of corneal reflection, from an image of an eye ball of a subject irradiated with the light by the illuminator, and captured by the imaging units (202, 203); and a calculator configured to calculate a fourth position indicating a curvature center of a cornea, based on a position of the light source, a third position on a display, the first position, and the second position, characterized in that -the calculator is configured to calculate a first straight line connecting a position of the light source and the second position, calculate a second straight line connecting the first position and the third position on the display, calculate the fourth position that is an intersection point of the first straight line and the second straight, line, calculate a first distance that is a distance between the first position and the fourth position, calculate a fifth position existing on the first straight line and indicating a curvature center of a cornea that includes a predetermined cornea curvature radius, and correct the fifth position to a sixth position existing on the first straight line, and at which a distance from the first position becomes the first distance. an illuminator including a light source that performs irradiation with light; a plurality of imaging units (202, 203); a position detector (351, 352) configured to detect a first position indicating a center of a pupil and a second position indicating a center of corneal reflection, from an image of an eye ball of a subject irradiated with the light by the illuminator, and captured by the imaging units (202, 203); and a calculator configured to calculate a fourth position indicating a curvature center of a cornea, based on a position of the light source, a third position on a display, the first position, and the second position, characterized in that -the calculator is configured to calculate a first straight line connecting a position of the light source and the second position, calculate a second straight line connecting the first position and the third position on the display, calculate the fourth position that is an intersection point of the first straight line and the second straight, line, calculate a first distance that is a distance between the first position and the fourth position, calculate a fifth position existing on the first straight line and indicating a curvature center of a cornea that includes a predetermined cornea curvature radius, and correct the fifth position to a sixth position existing on the first straight line, and at which a distance from the first position becomes the first distance. calculate a first straight line connecting a position of the light source and the second position, calculate a second straight line connecting the first position and the third position on the display, calculate the fourth position that is an intersection point of the first straight line and the second straight, line, calculate a first distance that is a distance between the first position and the fourth position, calculate a fifth position existing on the first straight line and indicating a curvature center of a cornea that includes a predetermined cornea curvature radius, and correct the fifth position to a sixth position existing on the first straight line, and at which a distance from the first position becomes the first distance.