A method of producing an aluminum nitride sintered body having an amount of total metal elements other than aluminum smaller than 100 ppm, a room temperature volume resistivity greater than 1.0×109 Ωcm and smaller than 1.0×1013 Ωcm, and a relative density of greater than 99.5% comprising the steps of, preparing an aluminum nitride raw material having an amount of total metal elements other than aluminum of smaller than 100 ppm, forming the thus prepared aluminum nitride raw material to obtain a formed body, embedding a metal member in the thus obtained formed body to obtain a metal including formed body, sintering the thus obtained metal including formed body under a temperature of 1850° C.-2200° C. and a pressure of 50 kg/cm2 to obtain a metal including member, in which said metal member is embedded in a substrate member made of said aluminum nitride sintered body, said substrate member is substantially divided into a first portion and a second portion by said metal member, and said first portion has a thickness of smaller than 10 mm, thereby obtaining said aluminum nitride sintered body as first portion of said substrate member.