Yes, cocoa powder comes from the cacao bean.
Cocoa powder is derived from the beans of the Theobroma cacao tree. The process involves harvesting the cacao beans, fermenting them, roasting them, and then grinding them into a paste called chocolate liquor. From this liquor, cocoa butter is extracted. What remains is then dried and ground into the fine powder we know as cocoa powder. The process differs from making cacao powder which involves less processing, retaining more of the bean's nutrients. Therefore, both products originate from the same bean.