A flux application state inspection device includes: an illuminator that irradiates a circuit board on which an electrode is disposed with visible light at a predetermined incident angle; an imaging device that is disposed above the circuit board such that an optical axis of the imaging device is orthogonal to the circuit board, and images light radiated from the illuminator to the circuit board and reflected from the circuit board to obtain a luminance image that indicates: the electrode as a dark portion; the base material portion as a bright portion having a higher luminance value than a luminance value of the dark portion; and a portion of the electrode on which the flux is disposed as an intermediate luminance portion having an intermediate luminance value between the luminance value of the dark portion and the luminance value of the bright portion.