To provide a high-toughness and high-strength bioceramic composite structure without impairing biocompatibility in the composite structure combining a core material of dense ceramics with sufficient strength or a metal and a porous skin material of a calcium phosphate-based sintered compact.

The composite structure 1 in which a plurality of single-core structural bodies 4 formed by covering an outer periphery of an elongated core material 2 with the porosity of 5% or less with the skin material 3 with the porosity of 25% or more and having pores communicating in three dimensions are gathered and bundled side by side is biologically used such as for a bone filling material.