Fluid heating device and manufacturing method for same

A fluid heating device (100) in which a heater (21) heats a fluid comprises a heating unit (22) that is formed so as to cover the periphery of the heater (21), and a supporting body (71) that is integrally cast with the heating unit (22) by the heating unit (22) being formed while the heater (21) is supported in a mold (60) for forming the heating unit (22).