An object is to provide a technology that relates to a protein nanocapsule capable of holding a substance to be encapsulated such as a drug and in which the protein nanocapsule can be introduced into a cell using a simple method and the encapsulated substance can reach a target in a cell.The present invention relates to a nanocapsule for a drug delivery system including, as a carrier material for encapsulation of a pharmacological component for a nanocapsule for a system of local drug delivery into a cell, a mutant chaperonin complex including an ATP hydrolysis activity-lowered GroEL subunit mutant as a GroEL subunit included in a ring structure and a subunit having GroES activity as a subunit included in an apex portion.
