Arai Hakuseki (新井 白石 March 24, 1657-June 29, 1725) is a Confucianist, poet and politician in Japan during the middle of Edo Period, who advised the Shogun, Ienobu. His personal name is Kinmi(君美) and Yogoro(与五郎). Hakuseki is the name under which he wrote. His father is a Kururi han samurai Arai Masazumi(新井 正済).

He was born in Edo and from the very early age displayed signs of genius. According to a story, at the age of three, Hakuseki managed to copy a Confucian book written in Kanji, letter by letter. Because he was born on the same year as the Great Fire of Meiwa and for being hot tempered that his brow would crease looking like 火 or 'fire', he was affectionately called Hi no Ko(火の子) or child of fire. He was a retainer of Hotta Masatoshi . But after Masatoshi was assassinated by Inaba Masayasu , the Hotta clan was forced to move from Sakura to Yamagata then to Fukushima and the domain's income declined. Hakuseki offered to leave, becoming a ronin and studied under a Confucianist, Kinoshita Jun'an . He was offered a post from the largest han, Kaga, but he offered the position to his fellow.

On 1693, Hakuseki was called up to serve by the side of Manabe Akifusa as his brain for the Tokugawa shogunate and shogun Tokugawa Ienobu. Under the top Roju, Abe Seikyo with the strong support from Ienobu, they launched Shotoku no Chi , a series of economic policies designed to improve the shogunate's standing. By minting new and better quality currencies, inflation was controlled. By calculating from trade records, Hakuseki deduced that fully 75% of gold and 25% of silver in Japan had been spent of trades with foreign countries, he implemented a new trade policy Kaihaku Tagaeichi Shinrei(海舶互市新例) to control the payments to Chinese and Dutch merchants by demanding that instead of precious metals to use products like silk, porcelaine, and dried seafoods for trading. He also simplified rituals for welcoming Joseon Dynasty's ambassadors against the opposition by Tsushima confusionist, Amamori Hoshu . While some of Hakuseki's policies were still carried out after Ienobu's death, after the 6th shogun, Tokugawa Ietsugu died and Tokugawa Yoshimune's rule began, Hakuseki left his post to begin his career as a proficient writer.

His works include:

• Hankanfu (藩翰譜) - A list of daimyo's family tree
• Koshitsu (古史通) - A work that detailed ancient history of Japan
• Oritaku Shiba-no-ki (折りたく柴の記) - A diary and memoire
• Sairan Igon (采覧異言)
• Seiyo Kibun (西洋記聞) - A work describing the West, based on Hakuseki's interview of a Jesuit priest, Giovannni Battista Sidotti
• Tokushi Yoron (読史余論) - A historical work

He was buried in Asakusa(current day Taito, Tokyo), Ho'onji temple but was later moved to Nakano, Tokyo, Kotokuji temple.