A sandwich panel includes a first plate member and a second plate member, each of which is metallic, a spacer unit which is metallic and formed in the shape of a rectangular frame, and a core member. The core member is arranged in a region surrounded with the spacer unit between the first plate member and the second plate member. The spacer unit is made up of a plurality of spacers that are formed as separate members. The first plate member and the second plate member are bonded to the core member and each of the plurality of spacers.