A spheroid composite includes: a substrate including a cell-adhesive porous base material and plural hydrophilic regions and hydrophobic regions that are disposed on the porous base material and formed by curing a photosensitive composition, wherein the photosensitive composition includes a branched polyalkylene glycol derivative having three or more polyalkylene glycol groups, each having a polymerizable substituent at a terminal thereof, and a tri- or higher-valent linking group that binds to the polyalkylene glycol groups; and spheroids formed in the hydrophobic regions on the substrate, the plural spheroids having a uniform size. A spheroid-containing hydrogel, which includes a hydrogel and two or more spheroids having a uniform size with a diameter of from 70 μm to 400 μm that are disposed in the hydrogel in such a manner that the two or more spheroids do not contact each other, can favorably maintain the function of the plural spheroids contained within the hydrogel.