To provide a contrast medium heating system capable of heating a contrast medium circulating inside a constant medium tube for connecting a contract medium container to a cock operated by an operator.

This contrast medium heating system is constituted of: the contrast medium tube usable as a substitute for a conventional contrast medium tube for connecting the contrast medium container to the cock operated by the operator, and heating the contrast media circulated in a lumen by circulating hot water around 37°C in an external cavity of a double-structure tube, which can be used without changing the length of the tube, to heat the contrast media circulating in the lumen; and a hot water circulating device used by being connected to the contrast medium tube outside a sterilization area on an operating table.