There are many questions regarding the origin of Mochi-gayu, but "Ononomiyanenjugyoji" (the precedents for annual events of Ononomiya) says that Mochi-gayu was already mentioned at Shusuishi (water office in charge of acquiring water and cooking porridge) in the Konin-shiki Code; moreover, Emperor Uda wrote that he introduced the folk custom into the imperial court during the Kanbyo era ("Udotennoshinki (the diary of Emperor Uda)," February 30, 890).
なお、餅粥の由来については不明な点が多いが、『小野宮年中行事』には弘仁式主水司に既に記載されていたと記され、宇多天皇は自らが寛平年間に民間の風習を取り入れて宮中に導入したと記している（『宇多天皇宸記』寛平2年2月30日条）。