A contact shape computing apparatus for detecting contact between a plurality of three-dimensional solid models and computing a contact shape between two solid bodies in contact with each other includes the following elements: a collision detector operable to detect a collision or contact between the two solid bodies; a contact plane setting unit operable to define a contact plane that passes through a common region of the two solid bodies; a contact problem solving unit operable to individually solve contact states of the solid bodies with the contact plane as half-contact problems; and a contact shape computing unit operable to compute the contact shape between the two solid bodies by uniting solutions of the half-contact problems for the associated solid bodies, the solutions being obtained by the contact problem solving unit.