A Study on the Countermeasures against International Computer Crime focusing on the Police Investigation Procedure. These days, much more intelligent, varied and advanced techniques for computer crimes have been used than for development of technology. In particular, it has been reported that the damages are enormous. Damages of some computer crimes can not be accurately reported. This study is to speculate specific types of computer crimes and obtain its prevention and countermeasures centering on the Police Investigation Procedure. In particular, it is to speculate international cooperation under the condition that global damages occur frequently due to preparation of advanced network environment.