SAN FRANCISCO — Bill Gates is stepping down from the board of Microsoft, the software giant he helped found more than four decades ago.

Mr. Gates said on Friday that he would also step down from the board of Berkshire Hathaway, the conglomerate run by his close friend, Warren E. Buffett.

“I have made the decision to step down from both of the public boards on which I serve — Microsoft and Berkshire Hathaway — to dedicate more time to philanthropic priorities including global health and development, education, and my increasing engagement in tackling climate change,” Mr. Gates wrote in a LinkedIn post.

For decades, Mr. Gates was the face of Microsoft. Known for his technical acumen and ruthless business practices, he helped to establish Microsoft’s Windows software as the primary system for the personal computer. Microsoft said Mr. Gates would remain a technical adviser to the company.