Photon counting computed tomography (PCCT) based on indirect conversion detectors took great interests from its low fabrication cost and easy handling. In order to satisfy both count rate requirements of over 2 Mcps/mm2 and spatial resolution requirements in PCCT, sub-mm pitch silicon photomultiplier array using silicon on insulator technology (SOI-SiPM) was fabricated and evaluated in this study. All SiPMs were formed in the bulk substrate layer and readout electronics was integrated on SOI layer. In this study, the basic performance of SOI-SiPM array prototype was investigated. Several sensor features, such as a fast recovery time around 16 ns and a gain of 1 × 105 were within requirements to realize Photon counting computed tomography. More detailed performance including electronics will be presented in conference.