Disclosed are a composition including a silane-based organic/inorganic hybrid material having a multiple bond and one or more organic metal compounds and/or one or more organic polymers, an organic insulator including the composition, an organic thin film transistor (OTFT) including the organic insulator and an electronic device including the OTFT. The organic insulator including the composition for preparing an organic insulator has increased charge mobility and an increased on/off current ratio, thus exhibiting improved properties, and the organic thin film transistor manifests uniform properties due to the absence of hysteresis.