An inclination detection method is disclosed, which uses a pair of electrodes placed so as to face each other and having a fixed positional relation and an electric conductor which can move between the pair of electrodes, wherein the pair of electrodes is in either a conducting state or a nonconducting state depending on the position of the movable electric conductor, the conducting state in a predetermined period is expressed as any one of a plurality of level values, and a movement state of the pair of electrodes is estimated based on which of the plurality of level values the conducting state takes on.