In a solid-state laser amplifying apparatus and a solid-state laser apparatus, a high-power laser beam can be produced in a high efficiency under stable condition. The solid-state laser amplifying apparatus is comprised of a solid-state element containing an activated solid medium; a flow tube for causing a cooling medium used to cool the solid-state element to flow therethrough; a light condensing device arranged so as to surround the solid-state element, for holding the flow tube by directly, or indirectly sandwiching the flow tube, an inner surface of which is formed as a diffusion/reflection surface; an excitation light source arranged outside the light condensing device, for emitting excitation light used to excite the solid-state element; and an opening portion provided with the light condensing device, for conducting the excitation light.