To form an intermediate layer for absorbing oxygen contained in materials between reinforcing fibers and silicon nitride so that delamination is not caused between the reinforcing fibers and the silicon nitride.

This laminate type silicon nitride sintered product reinforced with fibers is obtained by forming silicon nitride layers 21 comprising an oxynitride grain boundary phase containing nitrogen silicate grains and silicon on the surfaces and further forming a plurality of laminated fiber-reinforced composite layers 22 in the inner portion. The plurality of laminated fiber- reinforced composite layers 22 are obtained by dispersing inorganic reinforcing fibers in silicon nitride layers comprising oxynitride grain boundary layers containing silicon nitride grains and silicon. Therein, the cross section of the fiber-reinforced composite layers 22 is 10-40% based on that of the whole sintered product. The inorganic fibers are contained in an amount of 5-45 vol.% in the fiber-reinforced composite layers 22.