A living body indwelling object is capable of effectively suppressing the onset of inflammation derived from a porous structure made of a biodegradable polymer while preventing scattering of a plaque and a thrombus at the time of stent expansion. The living body indwelling object includes an expandable tubular stent and a porous structure made of a first biodegradable polymer, the porous structure being disposed to cover the stent, in which the stent includes a drug carrying portion containing a second biodegradable polymer and a drug, and a decomposition time of the porous structure is substantially the same as a decomposition time of the drug carrying portion or shorter than a decomposition time of the drug carrying portion.