Michikazu Ikeuchi admitted he had stabbed his father in the throat with the long wooden chopstick when a fight broke out in their Osaka home.
But local police said the 51-year-old man told them he did not mean to kill his father.
An Osaka police official said: ‘Ikeuchi told us he had tried to stop his parents from arguing and he did not intend to kill his father.
‘He said in his anger he waved the chopstick in front of his father but before he knew it, it got stuck in him.’
The chopstick used in the fatal incident was a large cooking utensil.
It is understood the man, who lives with seven people including his parents and his brother’s family, called emergency services after the incident.
Chopsticks have been a staple utensil in Japan since 500AD with the Japanese the first to create the now popular disposable set which are made of bamboo or wood.