Exemptions exist for antique sword collectors
Legislation against selling, making, hiring or importing samurai swords in England and Wales has come into force.
Those breaking the law face six months in jail and a £5,000 fine. Carrying a sword in public is already illegal.
Exemptions will cover swords which are used for re-enactments or antique weapons kept on display by collectors.
Eight years ago a councillor was killed by a man wielding a samurai sword in the office of Cheltenham Liberal Democrat MP Nigel Jones.
Anyone found guilty of importing samurai swords will face up to seven years in prison and an unlimited fine.
Samurai swords are part of Japanese history and genuine artefacts can change hands for large sums of money.
But in recent years there has been a trade in reproductions which can be bought over the internet for as little as £35 and they have been used in several attacks.
Last month a gang of youths, one armed with a samurai sword, attacked a 15-year-old boy in Newry, County Down.
On another occasion, a youth was seen brandishing a sword in Newcastle.
Chris James, who deals in antique military items, including Japanese swords, told the BBC he welcomed the legislation.
He said: "I don't have a problem with it if it stops youths getting hold of cheap reproductions."
Home Office Minister Vernon Coaker said: "The government takes violent crime very seriously and we are determined to do all we can to protect individuals and communities.
"Having undertaken a wide consultation we recognise that it is the cheap and easily available samurai swords that have been used in crime. That is why we have made sensible exemptions for genuine enthusiasts.
"This ban is part of our wider strategy to tackle serious violent crime. Later this year we will launch a new advertising campaign aimed at preventing young people carrying knives."
In 2000 MP Nigel Jones survived a samurai sword attack
A Home Office spokeswoman said the government had consulted collectors and martial arts groups as well as laws enforcement agencies.
Swords aged over 100 years will be exempt from the law, and defences will be in place for crown functions, museums and drama productions.
Alf Hitchcock, of the Association of Chief Police Officers (Acpo), said: "Throughout the consultation process the Association of Chief Police Officers has supported the government's position on the banning of samurai swords.
"As I have said on previous occasions, these are not the most common weapons for people to carry and use in violent crimes but nationally there have been some significant incidents, serious assaults and murders using a samurai sword.
"So we feel the introduction of a ban is much needed."
Currently 17 weapons, including knuckle dusters and batons are on the Offensive Weapons Order, which was created by the Criminal Justice Act 1988.