A bioassay substrate high in integration amount, free in grouping of substances, low in cost, and the like are provided. Specifically, a bioassay substrate includes detection surfaces S on which detection substances can be solidified, the detection surfaces S is provided on a surface of a disk form substrate capable of reading out record information optically, and the detection surfaces S is provided in groove structures (pits) provided in the surface of the substrate radially as viewed on the upper side at predetermined intervals. A bioassay system using the bioassay substrate and a readout system are also provided.