X-ray detecting devices and apparatus for analyzing a sample using the same are disclosed. A disclosed X-ray detecting device has an X-ray detector to detect X-rays emitted from a sample. The X-ray detector includes a collimator to collimate the X-rays, an electron trap to remove electrons included in the collimated X-rays, a window to transmit the X-rays and defining an interior space of the X-ray detector, a crystal to receive the X-rays which pass through the window and to generate a corresponding electric current, a field effect transistor to generate a signal in response to the electric current, and a vacuum pump to create a vacuum within the interior of the X-ray detector containing the field effect transistor and the crystal to suppress noise associated with at least one of the crystal and/or the field effect transistor.