Consumer prices in Japan were down 0.4 percent on year in October, the Ministry of Communications and Internal Affairs said on Friday.
That missed expectations for a decline of 0.3 percent following the flat reading in September.
Core CPI, which excludes volatile food prices, tumbled 0.7 percent on year - in line with expectations following the 0.3 percent drop in the previous month.
On a seasonally adjusted monthly basis, overall inflation lost 0.4 percent and core CPI eased 0.2 percent.
Individually, the biggest declines came from food, fuel, communications and recreation.