Overall consumer prices in Japan were up 3.5 percent on year in April, the Ministry of Internal Affairs and Communications said on Friday.
That was well above expectations for an increase of 2.5 percent and up from 3.2 percent in March.
On a seasonally adjusted monthly basis, inflation rose 0.6 percent - above forecasts for 0.5 percent and up from 0.4 percent in the previous month.
Core CPI, which excludes volatile food prices, was up 3.4 percent on year - matching forecasts and accelerating from 3.1 percent a month earlier.
On month, core CPI was up 0.5 percent - unchanged and in line with expectations.
