The present invention provides a medical fluid dispenser. Medical fluid to be additionally administered to an administration target such as a patient is supplied into a balloon, when a button is operated. As medical fluid is supplied into the balloon, the balloon inflates to store the medical fluid therein. The inflated balloon contracts using its own restoring force to discharge the medical fluid that has been stored therein. Thereby, an additional administration of medical fluid can be continued for a predetermined time period without the need for repeatedly operating the button.