To provide a game machine which facilitates the discovery of the illegal modification of electronic parts.

In the control board 800, a lattice-like pattern 810 is printed on top of a tally 910 applied on a seal 900 between both and the printing is made using an ink material removable with a chemical agent capable of erasing the tally 910 as well. As a result, after the peeling of the seal 900 off, the tally 910 left on the side of the control board 800 can not be erased without getting the pattern 810 put out on the control board 800 together with the tally 910. Thus, after the replacement of an IC chip 700 with the illegal part on the control board 800, a fake seal 900 and a fake tally 910 may be applied but the mark proving the erasion of the regular tally 910 is left somewhat on the control board 800.