A fluid-heating device for heating fluid includes: a heater having a heat generating part, the heat generating part being configured to generate heat upon application of current; an electric component configured to control the application of the current to the heater; a tank having an opening portion, the tank being configured to accommodate the heat generating part; a top-plate portion configured to close the opening portion of the tank, the top-plate portion being configured to form a fluid chamber through which the fluid flows; and a first communication port and a second communication port configured to allow the fluid to flow through the fluid chamber; wherein the electric component is provided on an outer side of the fluid chamber along the top-plate portion.