An apparatus for the electromagnetic spectrum or optical analysis of a material to be analyzed that is located in a product space, such as a container or tube, in particular for the photometric, spectrophotometric or image analysis of powder, bulk material, granules and the like, is provided with a measuring probe which is arranged in a housing and is provided with at least one radiation or lightmeasuring element, a measuring window, which is arranged in the path of rays in a wall of the housing, and with at least one detection element for the analysis. The measuring probe is formed and guided displaceably in the axial direction in such a way that at least part of the housing in which the measuring window is located enters through an opening into the product space in which the material to be analyzed is located, for the analysis. The at least one measuring window is arranged in at least one subregion of the circumferential wall of the housing. A sealing cap is located between a frontend face of the housing and the measuring window arranged in the circumferential wall, which sealing cap is at least partially still in the region of the opening (5) in the product space (3), and consequently covers the opening (5), in a retracted position of the measuring probe in which the measuring window is outside the product space.