USA and Canada are the only countries in the world with such restrictive laws on airsoft sports.
In fact, there is a complete ban of airsoft guns by the US Gun Control Act of 1968 (which was not amended since 1986), which made illegal possession of any weapon resembling a firearm — regardless of its make — punishable by up to five years in jail. The law applies to any airsoft guns, paintball markers and airguns that fire less than 6mm plastic pellets (which are not biodegradable), including replica firearms with even the most minute external resemblance to real ones.
As of today, each state of the USA has its own set of laws concerning airsoft sports; some make them completely legal, some require a permit or license to be obtained in order to play airsoft.
In some states such as Virginia and New Jersey, it is legal to own and use airsoft guns whereas California, Mexico, New York, and New Jersey completely forbid their use.
In Canada rules also vary from province to province. It is illegal for anyone under the age of 18 in British Columbia, Alberta, Manitoba, Saskatchewan, Ontario, Quebec, Newfoundland & Labrador to purchase any airsoft gun.
It is also illegal for anyone under 18 to carry an airsoft gun in public places.
The one exception is the province of Nova Scotia where it is legal for anyone between 14 and 18 years old to use an airsoft gun, but not own or buy one. A major problem with Canada’s current legislation is that it does not cover the situation where only the exterior shell of an airsoft gun is similar to a real firearm.
Laws such as this one have been highly criticized by Canadian law-abiding citizens and organizations such as “NARCO” (http://narcoairsoft.com/)
An airsoft match is defined as a prearranged and prepared scenario with the intent to engage in an exhibition of sport or an educational/training exercise with simulated weapons which expel plastic projectiles propelled by compressed gas. 
During the past decade, there has been an immense growth in the popularity of airsoft sports such as paintball and laser tag. Although it has become one of the most popular sports in Japan, America and Europe, the legality of these sports is still widely debated.
Today there are strict legal restrictions on airsoft sports in many European countries including “Denmark, Hungary, Austria, Norway, Finland, France, Germany, Italy, the Netherlands, Portugal, Sweden, and Switzerland.” 
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The UK has relaxed its laws on airsoft. It is legal to own an airsoft gun but illegal to fire it in a public place. According to government advice issued by the Home Office “Playing Airsoft” (the rules of the game) is legal under UK law. According to the Home Office, “Airsoft is a sport where participants remove the power from their replica firearms by using either gas or electric charges so the projectile has a muzzle velocity of fewer than 100 meters per second.” .
The debate on the legality of airsoft sports has not been resolved. The widespread violence in many countries such as America and China has led to further restrictions on these sports which may result in its elimination from those countries.