To accurately and speedily calculate high tide times and low tide times.

A CPU 10 of an electronic tide meter selects the input of a calendar and a region from an input part 14, reads the tide data of the selected region from a ROM 11 that stores tide data for each region for determining a tide estimation expression, obtains first tide data from the tide estimation expression with a first time interval and furthermore obtains second tide data with a second time interval that is shorter than the first one, thus extracting from the first data a range where the code of displacement in the first tide data, obtaining tide data with a small time interval only for the range, and hence accurately calculating high tide time and low tide time from the tide data.