According to one embodiment, a light source apparatus includes a semiconductor light emitting device, a mounting substrate, first and second connection members. The semiconductor light emitting device includes a light emitting unit, first and second conductive members, a sealing member, and an optical layer. The mounting substrate includes a base body, first and second substrate electrodes. The connection member electrically connects the conductive member to the substrate electrode. The conductive member is electrically connected to the light emitting unit electrode and includes first and second columnar portions provided on the second major surface. The sealing member covers side surfaces of the first and the second conductive members. The optical layer is provided on the first major surface of the semiconductor stacked body and includes a wavelength conversion unit. A surface area of the second substrate electrode is not less than 100 times a cross-sectional area of the second columnar portion.