Born in Musashi province in 1827, he inherited and continued the family business of dealing in raw silk. Following the opening of the port of Yokohama, he established a storefront called the Kame-ya, to sell silk thread.
In 1874, he became the president of the Yokohama kiito kaikaisha (Yokohama Raw Silk Revised Company); shortly afterwards, he also became the head of the Second National Bank.
Hara was elected to the House of Peers.
- "Hara Zensaburô" 原善三郎. Gôshô hyakunin 豪商百人. Bessatsu Taiyô 別冊太陽. Winter 1976. p144.