[Problem] To provide: a novel myocardial stem cell for transplantation that enables maintaining of a therapeutic effect on and/or preventative effect against cardiac arrest for a prolonged period； a method for producing said myocardial stem cell； and a cell preparation containing said myocardial stem cell. [Solution] The present invention pertains to: a production method for a myocardial stem cell to be used for the treatment and/or prevention of cardiac arrest, the method comprising a step for introducing into a myocardial stem cell a complex of a mitochondria-targeted carrier and a mitochondria activating agent； a cell produced by said production method and a cell preparation containing same； and a liposome used to produce said cell. The present invention is able to provide a myocardial stem cell that is capable of maintaining a therapeutic effect by cell transplantation and/or a preventative effect thereby for a prolonged period.
