The present invention relates to uncooled infrared detector with infrared absorption structure in which the supporting layer, detection layer, protecting layer, and dielectric layer construct .lamda./4 resonating absorbtion structure as a single body. In order to enhance the characteristic of uncooled infrared detector, it is essential for the infrared absorption layer to absorb incident infrared with high efficiency. The present invention is characterized in that the infrared detector with unified absorption layer includes an infrared detection film, a device protecting layer, a supporting layer for thermally isolated structure, and a dielectric layer, etc. in its absorption structure. Due to this characteristic, highly efficient infrared absorption is possible with much less thermal mass than the absorption layer for the structure of existing metal/dielectric/metal structure and regardless of the distortion of floating structure caused by fabrication fault rather than air cavity .lamda./4 structure.