A supply device that supplies a liquid to a liquid ejecting head, includes one or more tanks that house the liquid; a liquid flow path coupled to the one or more tanks and the liquid ejecting head; and a pressure-adjusting portion that adjusts a pressure in the one or more tanks. The one or more tanks are provided between the pressure-adjusting portion and the liquid flow path. The pressure-adjusting portion includes a communication path that communicates with the one or more tanks, a pressure chamber provided with a diaphragm and coupled to the communication path, and an urging portion that urges the diaphragm in a direction in which the pressure chamber expands.