The present invention relates to a composite film including a wavelength conversion layer and a diffusive reflection resin layer in a laminated state and being used in a semiconductor light emitting device, in which the wavelength conversion layer contains a phosphor material which absorbs a part or all of excitation light and is excited to emit visible light in a wavelength region longer than a wavelength of the excitation light, the diffusive reflection resin layer is selectively formed with patterning on one surface of the wavelength conversion layer, and a region on the one surface of the wavelength conversion layer where the diffusive reflection resin layer is not formed with patterning is a path of the excitation light which excites the phosphor material in the wavelength conversion layer.