The move comes after a spate of violent attacks on trains in recent years.
Ministry officials discussed the plan with an advisory panel on Wednesday.
Mixed reception from train riders
Train passengers had differing responses to the plan.
One said it would effectively deter violent incidents, which are increasing.
Another said that women might feel more secure, if the plan reduces the risk of molestation aboard trains.
Another person said cameras may help decrease antisocial behavior.
But some train riders expressed worries about privacy. One said some people do not want to be observed by others, and their loss of privacy was somewhat concerning.
Tokyo plagued by series of train attacks
Tokyo trains were the scene of several indiscriminate attacks in 2021.
A knife slasher on a running train operated by Odakyu Electric Railway left 10 people injured in August that year. The suspect reportedly told police after his arrest that he wanted to kill women who "looked happy," but that "anyone would do."
Two months later, a young man who said he was inspired by the Odakyu attack took out a knife on a Keio Line train bound for Shinjuku, and also started a fire inside the car. Seventeen people were injured, including a man in his 70s who was stabbed.
Attacks have also taken place on Japan's bullet trains, including an arson attempt on the Kyushu Shinkansen in November 2021.
In June 2018, a random attack on a moving Tokaido Shinkansen left one man dead and two women injured.
Railway operators concerned about costs
The Ministry of Land, Infrastructure, Transport and Tourism has been discussing the train camera plan with a panel of experts and railway operators.
Companies expressed an understanding of the need to enhance safety, but some voiced concerns about the cost burden.
An executive at a major private railway company in the Tokyo metropolitan area said it would incur enormous costs to install and maintain the camera systems.
An official at another major private railway said it has many trains operating over a wide area, so the company hopes for financial support from the government to help pay for the cameras.
Some Japanese trains already have cameras
Security cameras are already installed on some Tokyo trains, including all carriages of East Japan Railway Company's Yamanote Line and other lines in the Tokyo metropolitan area. Tokyu Railway's train cars also have cameras.
About 60 percent of Tokyo Metro subway carriages were equipped with cameras as of the end of April. Seventeen percent of Tobu Railway train cars had cameras as of the end of March.
In western Japan, about 30 percent of JR West's commuter and other trains had security cameras as of the end of April.
West Japan Railway said that 96 percent of its Sanyo Shinkansen bullet trains have cameras, and the rest are scheduled to get them by the end of this fiscal year. It said all other Shinkansen trains already have them.
Keio Corporation, which operated the train on which the October 2021 attack occurred, said 87 percent of its carriages had cameras as of the end of May. The company aims to install them in all cars by the end of this fiscal year.
Odakyu Electric Railway, operator of the train that was the scene of the August 2021 attack, has also accelerated its camera installation. It plans to have the devices on almost all its carriages by next fiscal year.
Expert: Cameras on trains are 'unavoidable'
Professor Abe Seiji of Kansai University, an expert on railway safety, said installation of security cameras on trains is "unavoidable."
He said any incident occurring in a place with a large number of people risks harming many of them.
Regarding the privacy issue, Abe said he is aware that recording images is controversial. He said informing passengers about the presence of the cameras would be a "meaningful measure."
Abe said finding a balance between safety and security while weighing the potential invasion of privacy is important, and the issue "should be discussed by society as a whole, whether society can tolerate it."