In a press statement, DoCoMo said it hoped the investment would allow it to improve its Linux products. The company was unavailable for any further comment.
NTT DoCoMo has already introduced 3G products equipped with MontaVista Linux: earlier this year DoCoMo chose MontaVista's Linux operating system for three of its FOMA 3G mobile phones. The Linux-based phones included the N900iL, the N901iC--both developed by NEC--and the P901i from Panasonic.
MontaVista Linux was designed to allow multimedia applications required by 3G handsets to work.
The Silicon Valley company was founded in 1999. NTT DoCoMo has 48 million customers.
Earlier this year O2 teamed up with NTT DoCoMo to offer its i-mode service in the UK.