holes and 6 a concaved hole for stocking the ball pieces numeral 7 depicts a hollow protruding circular arc section and when the main body connects with another main body the connection is done by hooking the rim of section 7 to a retainer 9 of a recessed circular arc shape cut portion 8 as best understood in connection with fig4 a and 4b numeral 10 depicts a ball piece fig2 is a top view showing the state in which two main bodies 1 are combined with each other this is the arrangement for a few number of players few number of concaved holes where the connection is done by making the rim of the protruding circular arc section 7 fit with the recessed circular arc shaped cut portion 8 by the retainer 9 advancing method of the ball piece 10 in this case will be explained now assume that a this side camp domain is the concaved holes 2 to 5 a mated side camp domain is the concaved holes 5 39 to 2 39 and the concaved holes 6 and 6 39 on the both ends of them are used for stocking the ball pieces then 40 ball pieces are put into the respective.