Abstract: An adjusting device of a coin operated amusement assembly includes a drive device mounted onto a back of a horizontal board of the coin operated amusement assembly. A transmission device is connected to the drive device. Two adjusting plates are respectively and wiggly mounted to two opposite side of the horizontal board and inserted into a corresponding one of two return passages of the coin operated amusement assembly. Two driven devices are respectively connected to the transmission device and a corresponding one of the two adjusting plates for lifting the two adjusting plates and adjusting the odds of the coin operated amusement assembly.