Around 85,000 copies of the book, printed in German, have been sold since it was first published a year ago, the BBC reported.
The Institute of Contemporary History of Munich (IfZ) initially planned to print 4,000 of the new annotated version of the Nazi leader’s anti-Semitic text, according to AFP.
But huge demand has prompted the publisher to produce many more copies that originally planned, with the sixth print run due to hit shelves later this month.
IfZ director Andreas Wirsching said that “the figures overwhelmed us”.
The work topped Der Spiegel’s non-fiction bestseller list for two weeks and retained a position on there for much of 2016.
According to the New York Times, the book sold out within hours on Amazon’s German site when it was first republished in January last year.
When the publication of the book - the first reprint since World War Two - was announced last year, some fears were raised that it could encourage neo-Nazi views.
According to AFP, Wirsching said in a statement: “It turned out that the fear the publication would promote Hitler’s ideology or even make it socially acceptable and give neo-Nazis a new propaganda platform was totally unfounded.
“To the contrary, the debate about Hitler’s worldview and his approach to propaganda offered a chance to look at the causes and consequences of totalitarian ideologies, at a time in which authoritarian political views and rightwing slogans are gaining ground.”
Up until 2015, the Finance Ministry of the State of Bavaria had exercised Hitler’s intellectual property rights over Mein Kampf, which prohibited its republication, the BBC explains.
But instead of banning the hate-filled tract (as countries such as Austria did) or simply allowing it to be published freely (as in the UK), a middle ground was found by only allowing the publication of an annotated version.
According to the Guardian, around 12 million copies of the partly-autobiographical work had been sold by the time WW2 ended in 1945.