A detection device including a substrate, a conductive pad, a conductive line, a photoelectric element, and an insulating layer is provided. The substrate includes a first region and a second region surrounding the first region. The conductive pad is disposed on the substrate and is located in the second region. The conductive line is disposed on the substrate and extends from the first region to the second region. The conductive line is coupled with the conductive pad. The photoelectric element is disposed on the substrate and is located in the first region. The photoelectric element is coupled to the conductive line. The insulating layer is disposed on the photoelectric element and extends from the first region to the second region. The insulating layer has a groove, and the groove is located in the second region. A manufacturing method of a detection device is also provided.