A gas supply mask apparatus comprises a mask main body which can be put on a mask wearer relatively simply and relatively reliably by extending a head-worn band such as an elastic bandage relatively simply and relatively reliably over the head of the mask wearer even when there is no head-worn string such as a rubber string at hand. A string attaching short hole and band attaching long hole are formed in each of the left and right end portions of the outer peripheral portion of the mask main body.
