Provided is a line-of-sight detection apparatus that outputs reliability of an estimation result of a line of sight when an eye to be a line-of-sight detection target is switched. The line-of-sight detection apparatus includes: an estimation target selection unit configured to select an eye of a line-of-sight detection target person as one of switchable line-of-sight detection modes; a line-of-sight estimation unit configured to estimate a line of sight of the line-of-sight detection target person in the line-of-sight detection mode; a reliability determination unit configured to determine, based on a first line of sight before the mode is switched and a second line of sight after the mode is switched, reliability of the second line of sight; and a line-of-sight direction output unit configured to output information on the second line of sight and the reliability of the second line of sight.