We theoretically study the Kondo effect in quantum dots with two orbitals and spin 1/2. The Kondo temperature TK is evaluated, as a function of energy difference Δ between the orbitals, using the scaling method. TK is maximal around the degeneracy point (Δ = 0) and decreases with increasing Δ following a power law, TK(Δ) = T K(0) (TK(0)/Δ)γ, which is understood as a crossover from SU(4) to SU(2) Kondo effect. The exponents on both sides of a level crossing, γL and γR, satisfy a relation of γL γR = 1. We compare this enhanced Kondo effect with that at the spin-singlet-triplet degeneracy for an even number of electrons, to explain recent experimental results.