This paper proposes a torque measurement method with two toy motors. The aim is to study the basic principles of electric motors and generators, that is, the Lorentz force law, in a laboratory experiment. The two motors are directly coupled and used as a driver and a generator, respectively. The generator functions as an electric brake and as a rotational speed sensor. Since the experimental setup does not need any torque tester, its handling is very easy. It is confirmed from the demonstration tests that the twin characteristics of the motors on motional electromotive force lead to reasonable results of torque estimation. (c) 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.