A method for producing a porous body comprising apatite/collagen composite fibers comprising the steps of gelling a dispersion comprising long apatite/collagen composite fibers having an average length of 10-75 mm, short apatite/collagen composite fibers having an average length of 0.05-1 mm, and a liquid freezing and drying the resultant gel to form a porous body and cross-linking collagen in the porous body.