To allow a CPU to stably read a constant of a resistor built in a piece under the condition of artificial vibration.

At finishing automatically identified mahjong pieces in mahjong play, a flexible board 7 which is connected to a CPU and formed of a circuit electrode is provided on a top plate 6 of a mahjong table. When arranged on the top plate 6 in contact with the side face of a top frame 8 with the piece bamboo 1b of a piece 1 turned down, the piece 1 is attracted at its lower side by a permanent magnet 9 and put in contact with a E point on the flexible board and an electrode 2 of the piece bamboo 1b is put in contact with the circuit electrode 10, so that the piece 1 is lifted at its upper side. At this time, the component force W' of the dead weight W of the piece 1 in the direction of a straight line L1 becomes the component force P' in the direction of a straight line L2, amplified at the distance ratio (L1/L2) of the straight line L1 to the straight line L2. Accordingly, the dead weight W of the piece 1 becomes an amplified contact force P in a vertical direction to the circuit electrode 10 and the circuit electrode 10 produces adequate deflection with the contact force P of the piece 1 to absorb and reduce the vibration of the piece 1.