An attitude angle control apparatus, an attitude angle control method, and an attitude angle control apparatus control program select an optimum attitude angle in a short period of time without being affected by disturbances at sea by measuring attitude angles and specific fuel consumption during navigation for any combination of a hull and propeller, create a statistical model based on the measured data, and select an optimum attitude angle on the statistical model. A marine vessel navigation control apparatus includes a constant-speed navigation controller and a trim angle controller. The trim angle controller includes an evaluated-value calculation module which calculates evaluated values of the trim angle, a storage medium, a statistical model creation module which creates statistical models using the evaluated values stored in the storage medium as an explained variable, and predetermined information including the trim angle as an explanatory variable, and a target trim angle calculation module which calculates a target trim angle based on the statistical model.