1. A method for deciding a handover of a mobile terminal based on context information for use in an environment with a plurality of networks, comprising: collecting context information from the terminal and networks; evaluating selection priorities of network interfaces for each transmission path for each application program based on the context information; and obtaining a handover decision value for selecting a best network interface from among the networks by applying a cost function to the evaluated selection priority, wherein the selection priorities are evaluated by using the following formula: ( S 11 S 12 … S 1 ⁢ n S 21 S 22 … S 2 ⁢ n ⋮ ⋮ ⋰ ⋮ S m ⁢ ⁢ 1 S m ⁢ ⁢ 2 … S mn ) = ( C 11 C 12 … C 1 ⁢ k C 21 C 22 … C 2 ⁢ n ⋮ ⋮ ⋰ ⋮ C m ⁢ ⁢ 1 C m ⁢ ⁢ 2 … C mk + ) ⊗ ( R 11 R 12 … R 1 ⁢ n R 21 R 22 … R 2 ⁢ n ⋮ ⋮ ⋰ ⋮ R k ⁢ ⁢ 1 R k ⁢ ⁢ 2 … R kn ) ⇒ ( C t ⁢ ⁢ 1 C t ⁢ ⁢ 2 … C tk ) ⊗ ( R 1 ⁢ j R 2 ⁢ f … R kf ) T = f ⁡ ( C t ⁢ ⁢ 1 ⁢ R 1 ⁢ j , C t ⁢ ⁢ 2 ⁢ R 2 ⁢ ⁢ j , … ⁢ , C tk ⁢ R kf ) ( 0 ≤ C ij ≤ 1.0 ≤ R ij ≤ 1 ) wherein Sij denotes an expectation value of an i-th application program when using a j-th network interface; Cij denotes a user's preference of j-th context information with respect to the i-th application program; and Rij denotes an influence of i-th context information in a j-th network.