There are provided a cell aggregate that can be used as a cell preparation in regenerative medicine, maintains the original characteristics of cells, and has high safety, and a method for simply and safely maintaining the cell aggregate size, the cell characteristics and viability suitable for use as a cell preparation in regenerative medicine. According to an aspect of the present invention, a cell aggregate maintaining method is a method including a maintenance process of maintaining a liquid containing a plurality of the cell aggregates at a temperature which is lower than a culture temperature of the cells and at which the liquid is not frozen.