A fluid supply apparatus which supplies a fluid to a medical apparatus includes: a pump mechanism including a first pump capable of carrying out a intake operation of a fluid and a feeding operation of the fluid, and a second pump capable of alternately carrying out a intake operation of the fluid and a feeding operation of the fluid a flow passage which includes an elastic member and which communicates with the pumps and supplies the fluid to the medical apparatus a pressure fluctuation detecting unit capable of detecting fluctuation in internal pressure in the flow passage and a flow passage deforming unit which deforms the flow passage according to the fluctuation in the internal pressure.
