The finance minister of Argentinia, who is approaching the end of almost five years in that turbulent office, said here yesterday that he will step down confident that his efforts to implant a free-market economy have taken root.

Jose Alfredo Martinez de Hoz, in Washington for the IMF-World Bank meeting, said he is unable to say who his successor will be when the current military government leaves office in April.

"But the important thing is that Argentina has accepted the principle that retaining something moderately good is better than trying to get something perfect."

As the architect of a financial policy that has taken 4 1/2 years to bring inflation down to an annual rate of 88 percent -- from the high 300s -- Martinez de Hoz speaks with poignant experience. In the 30 years before he took office, the minister pointed out during an interview, there were 30 finance ministers, none lasting more than two years.

"Not many Argentines thought we would last five years. But we have learned from our past mistakes," he said. It has not been tranquil. Martinez de Hoz, as the one civilian in a major ministry of the military government that seized power in 1976, early on because the one permissible open target for scathing public criticism.

Even though the military has established machinery for succession to another general in the presidency, the ruling junta of armed forces commanders still are disputing which it will be. And according to reports from Buenos Aires, the Navy's opposition to the free-market approach of Martinez de Hoz is a factor in the dispute.

Martinez de Hoz denied this, declaring that "the armed forces have approved the main policy guidelines" he laid down, incorporating them in the military's five-year plan to take effect as he departs in April.

Those guidelines have included a drastic reorientation from a state-planned to a free-enterprise economy, lowering of trade barriers and reduction of subsidies that used to permeate the society.

Among the "moderately good" results he proclaimed is reduction of inflation so that, while still high, "the trend is right." While the state formerly generated 40 percent of the gross domestic product, it now is responsible for 35 percent, and again he feels a trend has been established.

Asked how he responds to questions at meetings such as the current one about his country's notorious human rights record, Martinez de Hoz declared, "This time, no one has asked me." He acknowledged some heavy grilling in the past, although "not by finance ministers, who only discuss finances." He then offered an extensive argument that for the most part the "disappeared" in Argentina, estimated at more than 5,000, were active adversaries in an undeclared war.

Obviously pleased, though, that the question was not arising at the IMF-Bank sessions, he suggested that on the rights issue, as with the economy, Argentina has turned the corner.