A sensor switch includes two electroconductive terminals and two electroconductive beads. The electroconductive terminals are spaced apart along an axis. Each of the electroconductive terminals has an inner surrounding surface surrounding the axis and having an indented segment indented away from the axis. The electroconductive beads are movably and respectively disposed in the electroconductive terminals. When the sensor switch is placed such that the axis horizontally leveled, the electroconductive beads are respectively retained in the indented segments of the electroconductive terminals to be spaced apart from each other so that the sensor switch is in an open state.