1. A living body inspection apparatus comprising: an interval calculation section configured to obtain a heartbeat interval from a signal which indicates a heartbeat variation; a variation state calculation section configured to calculate an index which indicates a variation state of the heartbeat interval calculated by the interval calculation section; a comparison section configured to compare the index, which indicates the variation state of the heartbeat interval calculated by the variation state calculation section, with a predetermined reference value; and a determination section configured to determine a state of a restless legs syndrome, which is represented by RLS, based on a result of comparing by the comparison section.