The invention is to provide a process which can produce a fired body comprising aluminum titanate-based ceramics being excellent in thermal decomposition resistance and having high mechanical strength. The invention is a process for producing an aluminum titanate-based fired body, comprising a step of firing a shaped body of a starting material mixture which contains an aluminum source powder and a titanium source powder, and the aluminum source powder satisfies the following formula (1). In the formula, D90 is a particle diameter corresponding to a cumulative percentage of 90% on a volume basis and D10 is a particle diameter corresponding to a cumulative percentage of 10% on a volume basis, and these are determined from a particle size distribution of the aluminum source powder measured by a laser diffractometry. (D90/D10)1/2≧2  (1)