A bolometer type Terahertz wave detector comprises: a temperature detecting portion having a thin bolometer film formed on a substrate, a reflective film that reflects Terahertz waves formed on the substrate at a position facing the temperature detecting portion, and an absorption film formed on the top surface of part of an eave-like member that extends to the inside from the perimeter edge section of the temperature detecting portion and that absorbs Terahertz waves. The reflective film and the absorption film form an optical resonant structure. A thermal isolation structure is formed by a support portion that supports the temperature detecting portion such that it is separated from the substrate by a gap. The eave-like member is supported by the support portion so that it is separated from the substrate by a gap.