Americans' concerns about threats to their privacy rose sharply in one year, according to a new national survey.

At the end of 1978, 64 percent of 1,500 people polled were very or somewhat concerned about potential invasions of their personal privacy, compared to 47 percent in a poll that asked the same questions at the beginning of the year. Both surveys were made by Louis Harris.

Finance companies, credit bureaus, insurance companies, the Internal Revenue Service and credit-card companies were named in that order by most participants as the five groups that ask for too much personal information. The survey was conducted for Sentry Insurance.

The next five are: the CIA, the FBI, government welfare agencies, newspapers and other media, and banks.

Only 19 percent of those surveyed, however, said they think their privacy actually had been invaded.

In contrast, most categories of a leadership group of 600 government officials and business executives that also was surveyed responded with higher percentages when asked if their privacy had been invaded.

The most aggrieved group are police officers, 55 percent of whom said they had been victims of an improper invasion of privacy. Of the members of Congress and congressional aides surveyed, 39 percent think their privacy has been invaded.

There was an even more startling gap between the responses of the general public and the leadership group to questions about the media. All categories of the leadership group had majorities that think the media ask for too much personal information. More than three-quarters of bank executives and law enforcement officials criticized the media for being too intrusive. The general public survey, however, found only 31 percent who think that the media demand too much information.

By 62 percent to 25 percent, the public thinks a journalist's notes and sources should be protected from the courts - a position that has come under attack in a string of recent court decisions.

Executives in credit-card companies, banks, computer firms and law enforcement officials and member of Congress and congressional aides disagree.

The leadership group varied widely in its concerns about threats to privacy. Doctors, members of Congress and their aides and federal regulatory officials are more concerned than the general public. Senior executives of credit-card companies and banks are the least concerned. Only about one-third of each see reasons to worry.

The leadership group attitudes toward computers are far different from the general public's. While 63 percent of the public agree that the future use of computers must be restricted if privacy is to be preserved, the leaders - except the doctors - have greater faith in computers and in those who control their information banks and disagree that restrictions will be necessary.

Those people who said their privacy had been invaded were asked who was to blame for the invasion. Most often named were the police (19 percent), their employers (16 percent), and credit bureaus (8 percent).