There is provided a process for producing W-type ferrite having high magnetic properties by reducing compacting defects during wet compacting. Specifically, there is a provided a process for producing a ferrite sintered body having a main composition of the following formula (1): AFe2+aFe3+bO27 . . . (1) wherein 1.5≦a≦2.1, 14≦a+b≦18.5, and A is at least one element selected from Sr, Ba and Pb, the process comprising:a calcining step of obtaining a calcined body from a raw material compound; a first milling step of milling the calcined body to a predetermined size; a heat treatment step of holding fine powder obtained from the first milling step for a predetermined time in a predetermined temperature range in an atmosphere having an oxygen concentration of 10% by volume or less; a second milling step of milling the fine powder which has undergone the heat treatment step to a predetermined size; a step of wet compacting the fine powder which has undergone the second milling step in a magnetic field; and a sintering step of sintering the compacted body obtained by the wet compacting.