A wrinkle detection device (100) includes: a light projector (110) which, while moving relative to a layered body (40) formed by stacking electrodes (50) and separators (60), projects slit light onto an outermost one of the separators (60); a camera (120) which shoots a shape of the slit light on the separator (60); and a control unit (130) which calculates a gradient of the separator (60) on the basis of the shot shape of the slit light, and determines the existence of a wrinkle on the basis of the calculated gradient.