In this paper, the authors present an experimental modeling of an actual outboard engine, whose rigid body properties and dynamic characteristics up to 400 Hz are both to be expressed in the form of spatial matrices by the experimental spatial matrix identification method. To verify the basic validity and usefulness of the modeling based on the experimental identification, the test outboard engine is identified under detaching its flywheel. A set of spatial matrices are obtained in the condition. Then, the dynamic characteristics of the test engine under attaching its flywheel is predicted by computation. The natural frequencies and their associated natural modes are predicted with practically good accuracy.