The present invention provides an apparatus for inflation extrusion molding of pressure-sensitive adhesive sheet, including: one or a plurality of extruders; a die into which one or a plurality of resin materials are respectively introduced and which extrudes from an ejection opening the resin materials into an inflated cylindrical shape having a predetermined diameter in accordance with an inflation method; and two stabilizers facing each other at a predetermined angle so as to upwardly approach each other, and defining a space therebetween through which the cylindrically-shaped resin materials extruded from the die are passed to be deformed into a pressure-sensitive adhesive sheet in a flattened elliptical shape having a predetermined width, in which the stabilizers each have a plurality of air floating portions each of which blows air toward the resin materials; and the stabilizers rotate in one direction around the central axis of the cylindrically-shaped resin materials.