  Since governments give stimulus to firms and expect the spillover effect by
fiscal policies, it is important to know the effectiveness that they can
control the economy. To clarify the controllability of the economy, we
investigate a firm production network observed exhaustively in Japan and what
firms should be directly or indirectly controlled by using control theory. By
control theory, we can classify firms into three different types: (a) firms
that should be directly controlled; (b) firms that should be indirectly
controlled; (c) neither of them (ordinary). Since there is a direction
(supplier and client) in the production network, we can consider controls of
two different directions: demand and supply sides. As analyses results, we
obtain the following results: (1) Each industry has diverse share of firms that
should be controlled directly or indirectly. The configurations of the shares
in industries are different between demand- and supply-sides; (2) Advancement
of industries, such like, primary industries or other advanced industries, does
not show apparent difference in controllability; (3) If we clip a network in
descending order of capital size, we do not lose the control effect for both
demand- and supply-sides.
