The government spent more than $100,000 over the last several weeks preparing for President Carter's trip to nine countries that has now been postponed.

This cost estimate is based on figures, supplied by the government, on the expenses incurred in transporting a so-called "pre-advance" party of White House and other officials along the same route the President was to followed.

The pre-advance group left Washington Oct. 24 and traveled to each of the nine cities on four continents, covering 25,000 miles aboard one of the two Air Force jets normally used by the President. They returned to Washington Monday night after 15 days of travel.

It is likely that much of the cost of this trip - which probably totaled more than $150,000 - will have to be written off by the government. If and when Carter rescheduled his planned journey, additional pre-advance work will have to be done, White House officials conceded yesterday.

A pre-advance group always precedes a presidential trip to begin handling the thousands of details involved. It is made up of officials from various government agencies involved in presidential travel - yhe Secret Service, military aides, communications specialists, and the White House press, scheduling, advance transportation and television offices.

A number of State Deppartment officials also were included in the pre-advance group because the President's planned trip involved dealing with foreign governments.

By far, the largest expense for the pre-advance group that just returned was the operation of its aircraft, a Boeing 707 decorated with the presidential seal. The trip took 54 hours of flight time, costing more than $125,000.

This is based on figures, supplied by the White House, that it costs slightly more than $2,300 an hour to operate Air Force One. However, an airline industry official said yesterday that the actual cost for the Carter pre-advance trip undoubtedly was much more because aviation fuel is considerably more expensive overseas than it is in the United States.

In addition, the American party - numbering about 40, including the air-plane crew was entitled to travel expenses totaling about $2,500 a day for the group. For the 15 days, the group, according to State Department perdiem rates for overseas travel, probably spent about $40,000 for hotels, meals and other expenses.

These expenses do not include whatever costs were incurred by American embassies in the nine countries that the group visited.

The government will recoup part of the cost of the trip by billing transportation costs to nine officials of U.S. television networks and communications firms that went along on the trip to begin planning media coverage of the President overseas.

White House officials, protective of Carter's image of frugality, were reluctant to discuss the pre-advance expenses yesterday. Hugh Carter Jr., the President's cousin who is in charge of administration at the White House, said that if the trip is rescheduled in late December, which is under serious consideration, "I don't think you can say it's all been wasted."

But Hugh Carter conceded that another pre-advance group will probably have to go out when the President decides he can make the journey.