Weight sensor and balance controller

A weight sensor comprising:

• a pillar;
• an arm having an end fixed to said pillar and a free end;
• n holders, provided at n locations on a side surface of said arm arranged along a longitudinal direction, respectively, each of which is configured to hold a substance, n being a natural number equal to or greater than two;
• n strain value sensors, provided on said arm in association with n sums, respectively, each of which is configured to detect a strain value of said arm corresponding to a corresponding sum among the n sums, the corresponding sum being a sum of weights of the substances held by said holders ranging from a holder proximate to the free end to a m-th holder counted from said pillar, and m being a natural number ranging from 1 to n;
• and
• a weight calculation unit configured to calculate the n sums based on results of the detection of said n strain value sensors.