<p>Provided are a composting accelerator which comprises a mixture obtained by mixing (A) an organic matter having an arabinoxylan content of 10 wt.% or greater and (B) heat- resistant bacteria for assimilating an organic material, and optionally a humic acid and has a pH adjusted within a range of from 6.0 to 8.5; a composting accelerator comprising a mixture obtained by mixing the above-described organic matter (A) and calcium silicate (C) at a weight ratio ranging from 50:50 to 95:5; and a process for producing an organic fertilizer by using each of the above- described composting accelerators.</p>
