An air-conditioning apparatus is provided to which, even when a heat medium leaks from a heat medium circuit for some reason and air enters the heat medium circuit, the heat medium circuit can be automatically refilled with the heat medium before a pump is heated and damaged. When it is determined that a rotational speed of a pump is higher than an upper rotational speed limit, the controller determines that the heat medium is leaking from the heat medium circuit and performs a heat-medium-introducing and air-purging control process.