In this paper the fluid motion and hydrodynamic characteristics of the submerged hydrofoil of finite span is examined in detail. In §2 the velocity potential, in particular, its essential nature is discussed ; the three dimensional regular wave motions in the just abaft of the hydrofoil, in the limiting case that the Froude number is infinite, have analogy with the free vortex motions. In §3 the induced velocity, vertical and horizontal, is examined ; the former is due to free vortex and regular wave motion, the latter due to local disturbances and equates approximately to that of two dimensional motion. In §4 taking the assumption in the lifting line theory into account, the integral equation is introduced of determining the circulation distribution over the span of the submerged hydrofoil. In §5 the numerical solution of the integral equation is obtained, applying the Nystrom's method. In §6 the numerical examples are shown of effective circulation distribution, lift, vertical induced velocity and resistance of the submerged hydrofoil.