PROBLEM TO BE SOLVED: To provide an apparatus for measuring contact force which does not affect an essential performance for collecting electric power of a pantograph, can accurately obtain data of the contact force, is high in reliability, and reduces the cost.
SOLUTION: A strain gauge 2d is stuck to a coil spring 2a built in a collector head support 2. An output from the strain gauge 2d is inputted to a calculator 20. Acceleration of a collector head 1 is measured by an accelerometer 3 provided in the collector head 1 and inputted to the calculator 20. The calculator 20 converts the output from the strain gauge 2d into a load of the coil spring 2a. The contact force acting between the collector head 1 and a trolley wire 12 is found based on the load of the coil spring 2a and a signal of the acceleration.