A blood inspection system automatically repeats blood inspections at a plurality of times at a desired interval and a desired timing by chronologically coupling a supply of blood to each one of a series of blood inspection units. A change in a blood condition, such as a clotting time, is monitored so that a thrombus or the like is prevented from being formed and an associated medicine is prevented from being overdosed. The blood inspection system has a catheter providing a main flow path, a supply of a flushing liquid, a plurality of inspection units, a plurality of branched flow paths, an aspiration unit, and a switching valve for selectively coupling the main flow path to a determined inspection unit which has not yet performed an inspection.