Provided is a freezing method for aggregates of pluripotent stem cell-derived myocardial cells, including: (i) immersion of an aggregate of pluripotent stem cell-derived myocardial cells in a cryoprotectant, and (ii) freezing of the aggregate immersed in the cryoprotectant. Also provided is a frozen pluripotent stem cell-derived myocardial cell aggregate frozen using said method.