"My opinion of the EU is the following: A super state which polarizes countries' areas of competence but which at the same time is rather helpless because it only has a symbolic budget," Kaczynski told the daily Die Welt. "That is an artificial creation."
The president was completing a two-day visit to Germany on Thursday.
Poland, with its 38.6 million inhabitants, is widely considered the most powerful of the newer members of the EU, which expanded to 25 states in 2004 when it allowed mostly eastern European nations into its ranks.
But Kaczynski, who was elected last year, said it was a myth to think that all Europeans had a shared outlook.
"There is no European public opinion, rather national public opinions," he said.
As for the EU constitution, which was designed to provide the framework for the enlarged bloc, Kaczynski said it was "very open to interpretation." The constitution was rejected by Dutch and French voters in referendums last year.
Gay activists delay speech
During a visit to Berlin's Humboldt University, where Kaczynski toned down his comments on the EU somewhat, gay rights activists disrupted the Polish leader's speech to protest what they called his "homophobic policies."
The speech was delayed for about half an hour as dozens of protestors shouted "Solidarity without exclusion," a reference to the slogan of the labor movement that challenged Poland's Stalinist regime in 1980s.
"The Polish president is known for his hostile political stance towards gays and lesbians," the editor of a Berlin gay magazine, Holger Wicht, said as he approached Kaczynski. "He is an anti-democrat."
When the noise died down, Kaczynski responded by saying he would not persecute gays but did not believe homosexuality should be encouraged because gays did not have children.
"I do not plan to persecute homosexuals or to hinder their careers," he said. "But there is no reason to encourage it because it would mean that mankind would slowly die out."
The president provoked the wrath of Polish gays when he banned a gay pride march in Warsaw last year while still mayor of the capital.