To provide a method and device for inflating a tire in a good condition and short time.

In this method, an orifice for inflation is formed between a first keeper 13 of a rim 10 and a first bead 21, where inside enclosures 20, 32, the rim 10 of a tire 20 and beads 21, 22 are accommodated. Then compressed air is introduced into the orifice and the tire 20 is inflated by closing the orifice. The inflated tire is fixed to the rim 10 in an airtight condition. Before forming the orifice, the first bead 21 is positioned in the axial direction with respect to the outside of the first keeper 13, and the second bead 22 is fixed to a second keeper 14 in an airtight condition. Then the first bead 21 is compressed sporadically for forming the orifice.