An in vivo-implantable medical device includes a housing that includes a body part and a protruding part, and that forms a sealed inner space; a power-receiving coil in a part of the inner space and that receives power by interlinking with external magnetic flux generated by an AC current flowing in an externally located power-transmitting coil; and a circuit substrate including a power reception circuit electrically connected to the power-receiving coil. The body part includes a metallic biocompatible material and the protruding part includes a non-metallic biocompatible material. The protruding part is structured so that, for a magnetic path along which the external magnetic flux passes, a magnetic path in which the magnetic flux interlinks with the power-receiving coil while avoiding the body part is formed, and the protruding part reduces eddy current loss caused by eddy currents generated by the external magnetic flux interlinking with the body part.