In Tokyo alone, 18 people were hospitalised due to suffocation after eating the New Year delicacy, and three of them died, a fire department official said.
The Yomiuri Shimbun newspaper said the death toll from rice cake accidents reached nine by Friday across the nation and 13 others were in a serious condition.
During the New Year period, one of Japan's biggest holidays, families traditionally cook "ozouni" soup and put the sticky rice cakes in the vegetable broth.
Every year, several Japanese die after choking on rice cakes.