PROBLEM TO BE SOLVED: To provide a water level detection device capable of detecting, on early stage, insulation reduction of an electrode bar for water level detection.SOLUTION: In the water level detection device, a plurality of electrode bars 3 having different lower end positions are installed within a water level detection cylinder 2 and when a current flows between each electrode bar 3 and the water level detection cylinder 2, in the case where a resistance value is greater than a threshold value, a signal indicating the presence of water is outputted but in the case where the resistance value is smaller than the threshold value, a signal indicating the absence of water is outputted, thereby detecting a water level. In the electrode bar 3 at a higher position side, the signal indicating the presence of water is outputted more easily than in the electrode bar 3 at a lower position side. When detecting the presence of water in the electrode bar at the higher position side and detecting the absence of water in the electrode bar at the lower position side, occurrence of conflict is detected.