When expressway and roads coexist, it is necessary to establish a reasonable traffic share between them. It may be practiced by the regulation of toll-rate of expressway. But at an occasional traffic congestion, the reasonable share is disturbed, so that some traffic control means should be taken. In this paper, we deal how to control inflows on expressway, from a viewpoint of the optimal share between expressway and roads. The minimization of total travel cost in a system is aimed under traffic equilibrium conditions. The problem is formed as a two-stage programming model, and a simple example solving the problem is showed.