A motion state detection method which uses a pair of electrodes, facing each other to fix mutual positional relationship, and a movable spherical conductor disposed between the pair of electrodes, putting the pair of electrodes into either a conduction state or a non-conduction state and includes: defining a plurality of level values determined by the proportion of a duration of the conduction state in a unit time period and calculating a level value in the unit time period among the plurality of level values as a first level value adding a second predetermined value to the first level value to calculate a second level value and calculating the sum of squares of a plurality of first level values in a plurality of consecutive unit time periods as a first detection value and calculating the sum of squares of a plurality of second level values as a second detection value.
