This figure represents a 17 percent increase over the same period in 2007.
"We are strengthening the crackdown on child porn as society becomes more aware of the issue, and child porn is getting rapidly copied and spread on the Internet," Takafumi Ozawa of the National Police Agency said.
According to the National Police Agency, the number of Japanese CP prosecutions has tripled over the past four years; with around 40 percent of these cases involving the Internet.
"It's difficult to say how widespread child porn is," Ozawa said. "This is probably only a small part of what's out there."
While Japan and Russia are alone among the "Group of Eight" countries to not ban the simple possession of child pornography, the Japanese Parliament's lower house is set to debate a bill in September that would outlaw the possession of child porn.
"It doesn't surprise me that there is a growing issue with child pornography in both Japan and Russia because they do not ban the possession of CP," ASACP CEO Joan Irvine said. "Data from the ASACP CP reporting hotline indicates that the largest distribution of commercial CP is from organized crime in Japan (five percent) and Eastern European Bloc countries (90 percent)."
"These countries need to accept responsibility for what is occurring within their borders," Irvine added.