1. An attitude angle control apparatus which controls an attitude angle of a part of a marine vessel, comprising: a measuring device for measuring the attitude angle of the part of the marine vessel and specific fuel consumption of the marine vessel or alternative values relating to the specific fuel consumption of the marine vessel; a statistical model generator for generating a statistical model based on data from the measuring device; and an attitude angle controller for selecting an optimum attitude angle of the part of the marine vessel based on the statistical model generated by the statistical model generator.