To improve the spatial resolution of positron annihilation spectroscopy (PAS), a system to produce an intense positron microbeam was developed in AIST. A slow positron beam, which was produced by an electron linear accelerator, was focused by a lens onto a remoderator to enhance its brightness. The brightness-enhanced beam with an intensity of approximate to 1 X 10(6) e(+)/s was extracted from the remoderator and focused onto the sample by a lens. The beam size at the sample was 25 gm, which is more than two and half orders of magnitude smaller than that in the magnetic transport system (approximate to 10 mm). Hence, the spatial resolution of PAS with an AIST positron microbeam can be drastically improved relative to PAS using conventional methods.