A new step-type recording wave gauge with the application of micro-processor has been developed.
　There often appeared troubles for measurement due to contamination of the surface of electrodes and adhesion of seaweeds to the wave staff, in usual wave gauge of this type. We have introduced a new technique of signal processing with software in order to avoid these troubles. The measurement of water elevation in the new wave gauge is done by memorizing the magnitudes of an electric current on electrodes sampled every a definite time interval and then running the codes as display of either in or out of water, given electrodes, which are made based on the difference between just sampled current value and the value memorized before one time interval. As water elevation, thus, is determined from the relative values of an electric current on each electrode, the effect of water, running down on the wave staff and the above-mentioned troubles in usual wave gauge of this type can be avoided.
　The new step-type recoridng wave gauge is used on the oil platform at Agaoki Station in the japan Sea. As a result, this newly developed wave gauge can be used for wave observation without cleaning for about one year.