A line of sight detection device, comprising: a measurement unit (11, 17) that measures a movement of an eyeball of a subject wearing eyeglasses, the measurement unit (11, 17) including an eyeball imaging camera and an image processing device; a gaze point detection unit that detects a gaze point of the subject in a forward field of view of the subject based on a result of measurement by the measurement unit (11, 17); a transmission point detection unit that detects a transmission point at which a line of sight of the subject toward the gaze point passes through a lens of the eyeglasses based on the result of the measurement by the measurement unit (11, 17); and a display control unit that causes gaze point information indicating a position of the gaze point to be displayed at a display unit in superimposition on an image of the forward field of view and causes transmission point information (25, 26) indicating a position of the transmission point to be displayed at the display unit in superimposition on a lens image (22, 23) showing the lens of the eyeglasses, wherein the display control unit causes the image of the forward field of view on which the gaze point information is superimposed and the lens image (22, 23) on which the transmission point information (25, 26) is superimposed to be displayed in separate regions from each other, wherein the line of sight detection device further includes: a forward field of view camera; an infrared light emitting diode; a dichroic mirror configured to reflect infrared light and transmit visible light; and a headband, wherein the forward field of view camera, the eyeball imaging camera, the infrared light emitting diode, and the dichroic mirror are attached to the headband such that, if the headband is put on the head of the subject wearing the eyeglasses, the dichroic mirror is placed in front of the eyeglasses and the forward field of view camera, the eyeball imaging camera, and the infrared light emitting diode are placed above the eyeglasses, wherein infrared light irradiated by the infrared light emitting diode is reflected by the dichroic mirror to illuminate the eyeball of the subject, wherein the eyeball imaging camera captures a moving image of the eyeball illuminated with the infrared light. a measurement unit (11, 17) that measures a movement of an eyeball of a subject wearing eyeglasses, the measurement unit (11, 17) including an eyeball imaging camera and an image processing device; a gaze point detection unit that detects a gaze point of the subject in a forward field of view of the subject based on a result of measurement by the measurement unit (11, 17); a transmission point detection unit that detects a transmission point at which a line of sight of the subject toward the gaze point passes through a lens of the eyeglasses based on the result of the measurement by the measurement unit (11, 17); and a display control unit that causes gaze point information indicating a position of the gaze point to be displayed at a display unit in superimposition on an image of the forward field of view and causes transmission point information (25, 26) indicating a position of the transmission point to be displayed at the display unit in superimposition on a lens image (22, 23) showing the lens of the eyeglasses, wherein the display control unit causes the image of the forward field of view on which the gaze point information is superimposed and the lens image (22, 23) on which the transmission point information (25, 26) is superimposed to be displayed in separate regions from each other, a forward field of view camera; an infrared light emitting diode; a dichroic mirror configured to reflect infrared light and transmit visible light; and a headband,