A reproducing head including a read element, first and second electrodes provided at the opposite ends of the read element, a ground electrode provided between the first and second electrodes, a first constant current circuit for passing a first constant current between the first electrode and the ground electrode, and a second constant current circuit for passing a second constant current between the second electrode and the ground electrode. The reproducing head further includes a computing unit connected to the first and second electrodes for synthesizing an output from the first electrode and an output from the second electrode, and a storing unit having a table showing the relation between a synthetic value computed by the computing unit and the outputs from the first and second electrodes.