An electrical machining method comprises machining a workpiece by an electrical machining device comprising an electrode; increasing a feedrate of the electrode at a first acceleration if a discharge current passing through the electrode and the workpiece is lower than a discharge current reference; and decreasing the feedrate of the electrode at a second acceleration if the discharge current is higher than the discharge current reference, wherein the second acceleration has an absolute value higher than that of the first acceleration.

An electrical machining method comprises machining a workpiece by an electrical machining device comprising an electrode; increasing a feedrate of the electrode at a first acceleration if a discharge current passing through the electrode and the workpiece is lower than a discharge current reference; and decreasing the feedrate of the electrode at a second acceleration if the discharge current is higher than the discharge current reference, wherein the second acceleration has an absolute value higher than that of the first acceleration.

A controller used for irradiating a laser beam to an object from a machining head at a reference gap position is provided. The controller includes a gap sensor for detecting an amount of gap between the machining head and the object, a gap position command calculation part for producing a gap position command, a servo mechanism for driving the machining head to the reference gap position, a servo position deviation reading part for reading an amount of position deviation of the servo mechanism, a position gain calculation part for calculating a corrected position gain of the servo mechanism, based on the amount of position deviation of the servo mechanism and a position gain replacing part for replacing the position gain of the servo mechanism with the corrected position gain.