The Soviet Union's longtime minister of culture was retired from his post today, and given the largely ceremonial job of first vice president.

Pyotr Demichev, 68, a chemical engineer by training whose political career began in the Moscow city party, was for 12 years head of the vast bureaucracy that controls literature, the arts and Soviet intellectual life.

His retirement was announced today at the Supreme Soviet, the national legislature, by Yegor Ligachev, the second-ranking member of the Communist Party, with responsibilities for personnel and ideology.

There also were indications of the ascendancy of Anatoliy Dobrynin, former longtime Soviet ambassador to Washington, The Associated Press reported. Dobrynin, who today took over his duties as head of the Foreign Affairs Commission of one of the parliament's two houses, also was named to the influential Central Committee Secretariat, replacing Boris Ponomarev, who was dropped from the Politburo in March.

The Cultural Ministry had been one of the last of the major Moscow ministries to feel the impact of the leadership of Mikhail Gorbachev, who has been gradually putting his own generation in key party and government jobs.

So far, Demichev's replacement has not been announced, making it difficult to judge the impact of his departure on the arts world.

Although the Cultural Ministry commands great power, Demichev has been viewed largely as a functionary who carried out the Kremlin's shifting policies on the arts. He was named culture minister in November 1974, the same month that Russian author Alexander Solzhenitsyn was deported after his book "Gulag Archipelago" was published in the West.

Demichev remains a candidate member of the Politburo, and his appointment to replace the retiring Vasily Kuznetsov as first vice president indicates that his performance as cultural minister has not come under serious criticism.

In the 15 months since Gorbachev came into office, there have been scattered signs of liberalization in the arts. Several new political plays have been staged that frankly criticize the self-isolation and cynicism of party leaders and the deadening effects of a tradition of censorship.

Once-banned poets are being rehabilitated, once-criticized rock bands are giving Moscow concerts, satirists have become bolder before larger audiences and a few films that for years were unofficially blacklisted are shown in theaters and on television.

But despite these isolated signs of movement, many Moscow intellectuals are loath to declare a new era, noting until now that no clear direction in the field of culture has come from the top.

Many among the intelligentsia have long considered the exit of Demichev a prerequisite for any kind of widespread liberalization in culture. But, they have cautioned, much would depend on his replacement and on the pressures from Ligachev, a key figure widely regarded as a conservative on ideological issues.