A shoe includes an upper having a heel portion that has a rear wall adapted to extend around the heel of a foot. At least one adjustment pad is attached loosely to the rear wall within the heel portion. The adjustment pad includes an intermediate part, first and second ends on two opposite sides of the intermediate part, a first surface confronting the rear wall, and a second surface opposite to the first surface. A strap passage unit is provided on the rear wall. A strap is attached to the adjustment pad, and passes movably through the strap passage unit. When the strap is pulled to move through the strap passage unit, the strap is tensed, and the adjustment pad is moved inward so as to abut against the foot in the shoe.