The Carter administration has decided to elimanate restrictions on American tralvel to Cuba, Vietnam, Cambodia and North Korea.

In addition to removing the prohibition on using a U.S. passport for such travel without special permission, the Treasury Department restrictions on cashing travelers checks, paying hotel bills, changing currency and other such travel transaction s are expected to be lifted, U.S. officials said.

The decision, which one official called "long overdue," does not so much signal changes in U.S. policy toward the four nations as it reflects President Carter's commitment to freedom of movement for U.S. citizens, official said.

The executive order imposing the restrictions must be renewed every six months. The current order expires March 18, and it will simply be allowered to lapse.

The four countries are the only na- tions to which the government presently seeks to bar travel by its citizens.

It always has been possible for members of Congress, journalists, scholars, public health officials, some athletes and some people travelling for humanitarian reasons to get the restrictions removed from their passports.

The four nations, however, have taken widely different attitudes toward visits by Americans.

No American has traveled to Cambodia since the travel restrictions were imposed in 1975 following the fall of the American-supported government and establishment of a Communist government.

Restrictions on travel to Vietnam went into effect about the same time following the military victory of the North Vietnamese and Vietcong, but several Americans have been allowed to make visits, some of them without receiving U.S. government permission and others on U.S. government business seeking information about missing U.S. servicemen.

North Korea was placed on the list at the time of the Korean War, and South Korea recently has made clear that it hoped the travel restriction would continue.

Only small mnumbers of Americans, mostly journalists and scholars, have visited North Korea.

In contrast to the Asian countries, Cuba has been visited by thousands of Americans since the restrictions were imposed in 1960.

Many of them have not used their U.S. passports, by arrangement with the Cuban government. The U.S. restrictions prohibit the useof a U.S! passport, but not the travel itself.

There is no direct air travel between Cuba and the United States, but groups would be able to charter planes in the absence of travel curbs. In addition, travel via jamaica, Mexico and Canada would continue to be avaible.

Numerous business executives, tourists and other Americans are expected to apply for trips in the coming months.

THe liflting of travel restrictions is the first concrete action the carter administration has taken toward better relations with Cuba. Next on the agenda are talks about extending the anti-hijacking treaty that is due to expire April 15.