The optical module includes a first optical waveguide part including a first waveguide core, a second optical waveguide part including a second waveguide core and provided such that the second waveguide core and the first waveguide core are positioned partially close to each other so that a light propagating in one of the first and second waveguide cores can be coupled to the other of the first and second waveguide cores, an electro-optic material layer provided between the first and second waveguide cores and formed from an electro-optic material, and an electrode for applying an electric field to the electro-optic material layer so that the refractive index of the electro-optic material layer varies and the optical coupling coefficient between the first and second waveguide cores varies.