Ihara Saikaku (井原 西鶴, 1642 – September 9, 1693) was a Japanese poet and creator of the "floating world" genre of Japanese prose (ukiyo-zōshi).

Born as Hirayama Tōgo (平山藤五), the son of a wealthy merchant in Osaka, he first studied haikai poetry under Matsunaga Teitoku and later studied under Nishiyama Sōin of the Danrin school of poetry, which emphasized comic linked verse. Scholars have described numerous extraordinary feats of solo haikai composition at one sitting; most famously, over the course of a single day and night in 1677, Saikaku is reported to have composed at least 16,000 haikai stanzas, with some sources placing the number at over 23,500 stanzas.Later in life he began writing racy accounts of the financial and amorous affairs of the merchant class and the demimonde. These stories catered to the whims of the newly prominent merchant class, whose tastes of entertainment leaned toward the arts and pleasure districts.