The judge explained her decision on February 11 by saying that it was her personal belief that the book -- titled "Enlightened by Belarusness" -- might negatively affect the country's political and social stability.
The book was written was Ales Byalyatski, the leader of the Vyasna (Spring) human rights center.
In June, Belarusian customs officers confiscated copies of the book as Byalyatski's colleagues were bringing them into Belarus from Lithuania.
Tatsyana Ravyaka of Vyasna filed a lawsuit, saying the move was illegal.
Byalyatski was sentenced in 2011 to 4 1/2 years in jail on tax-evasion charges that his supporters say were politically motivated.
Amnesty International has declared Byalyatski a prisoner of conscience.