A hydrogen gas supplying apparatus includes a switching section configured to output, in accordance with switch instructions, one of a hydrogen-containing gas that contains hydrogen and a non-hydrogen-containing gas that does not contain hydrogen, an output section through which the gas that has been output from the switching section is supplied to a subject, and a controller configured to send the switch instructions to the switching section in accordance with an elapsed time and to control an amount of hydrogen that is output from the switching section. The controller controls an amount of hydrogen output per unit time during a first period from a start of switching from the non-hydrogen-containing gas to the hydrogen-containing gas to be greater than an amount of hydrogen output per unit time during a second period successively following the first period.
