An optical compensation film capable of contributing to improvement in a viewing angle characteristic of a liquid crystal display device, especially an IPS mode liquid crystal display device is proposed. A composition comprises at least one onium salt, at least one rod-like liquid crystalline compound, and at least one additive capable of promoting a vertical alignment of molecules of the rod-like liquid crystalline compound at an air interface; and an optical compensation film comprising an optically anisotropic layer formed of the composition are disclosed.