Petras Kaminskas was born in Stumbriškiai village, Pušalotas rural district, Panevėžys county. His mother died when he was six and he was brought up by his father. In 1940, he finished a six-form primary school in Pušalotas and continued at Panevėžys 1st Boys’ Gymnasium, which he finished in 1947. In the same year he became a student of the Forestry Faculty of Vilnius University. In 1949, during the operation of mass deportation ‘The Surf’, Petras Kaminskas was deported to Irkutsk region. In 1956 he was released from exile and soon returned to Lithuania. In 1964, Kaminskas filed a request with Vilnius University regarding his school-leaving certificate. The document was sent to him.