Disclosed is a method and apparatus for manufacturing a melt-blown fabric web, by which a melt-blown fabric web having improved filament cohesion and excellent bulky characteristics and sound-absorbing performance is manufactured. The apparatus includes a heat extruder for heating a thermoplastic resin composition and extruding the melted thermoplastic resin, a melt-blown fiber spinner for spinning the extruded thermoplastic resin as a melt-blown fiber in a filament form, a variable gas injector for injecting gas whose injection speed and injection quantity are continuously changed at random to the melt-blown fiber spun from the melt-blown fiber spinner to cause the injected gas to collide with the spun melt-blown fiber, and a collector for collecting the melt-blown fiber, which is spun from the melt-blown fiber spinner and collides with the gas, to form a melt-blown fabric web.