PROBLEM TO BE SOLVED: To provide a blink detection device that copes with a fact that a half-blink in feeling sleepy cannot be caught when a threshold of an eye-opening degree is set to a comparatively low eye-opening degree suitable to accurately catch a normal blink but there is a risk of erroneous determination of, especially, normal awakening by increasing a degree to allow the opening/closing of eyelids in terms of noise not being a blink to be erroneously determined as a blink when the threshold is set to a higher eye-opening degree, in a case where a blink is detected based on time versus eye-opening degree data.SOLUTION: Existence of a normal blink is determined when an eye-opening degree reciprocatively crosses both of a comparatively high threshold and a comparatively low threshold. Existence of a half-blink is determined when the eye-opening degree reciprocatively crosses only a comparatively high threshold without lowering to be a comparatively low threshold.SELECTED DRAWING: Figure 1【課題】瞬きを時間対開眼度のデータに基づいて検出するとき、開眼度の閾値を通常の瞬きを的確に捉えるに適した比較的低い開眼度に設定すると、眠気を催してきたときの半瞬きを捕捉できない。しかし上記の閾値を高くすると、瞬きではない瞼の雑音的開閉を瞬きと誤判する度合が増大し、特に正常な覚醒状態の判断を誤らせる虞れがあることに対処した瞬き検出装置を提供する【解決手段】開限度が比較的高い閾値と比較的低い閾値の両方を往復して横切ったとき通常の瞬きがあったと判断し、開眼度が比較的低い閾値まで低下することなく比較的高い閾値のみを往復して横切ったとき半瞬きがあったと判断する。【選択図】図1