To provide a fraudulence prevention structure for pachinko machines which yields effect for the prevention of the insertion of a piano wire in a wider range along with its inexpensive realization and its higher versatility and further achieves a higher effect for the defence against the destruction of the function of preventing the insertion of the piano wire. ピアノ線の挿入防止効果を広い領域で発揮でき、かつ汎用性高く低コストで実現でき、更にピアノ線挿入防止機能への破壊行為に対する防禦効果の高いパチンコ機の不正防止構造を提供する。 - 特許庁