The Tokyo Regional Taxation Bureau discovered Friday that two personal computers that may contain personal data on nearly 470,000 taxpayers may have been stolen.
The bureau has filed a report with police.
Police suspect the two computers were stolen from the tax bureau and have launched an investigation.
One of the two computers disappeared from the bureau's tax collection section, which deals with tax delinquencies, while the other vanished from the second taxation section, which collect taxes from corporations, the officials said.
The two computers contained personal data on taxpayers, including their names and addresses, they said.
Officials kept data on some 470,000 individuals in the two computers for their tax work.
Once relevant work has been completed, the officials are supposed to delete such data, according to the tax bureau's ordinary procedures.
The taxation bureau officials said they are not sure whether the data in question have been deleted from the stolen computers.
Since passwords are required to use the computers and the personal data have been encrypted, the officials said it is unlikely the data will be abused.
