Apparatus for checking value documents, in particular bank notes, comprising - at least two radiation sources (24, 25) for emitting electromagnetic radiation by means of which a value document is irradiated, - at least one sensor for detecting the electromagnetic radiation reflected and/or transmitted by the value document and generating corresponding sensor signals, with components ( R k) assigned to the radiation sources (24, 25), wherein the sensor signals are corresponding reflection and/or transmission signals, and - an evaluation device, which is designed to check the value documents on the basis of corrected sensor signals and to derive these corrected sensor signals ( BR; r 1) from the sensor signals taking into account at least one spectral property ( S k ( λ), S ki; a k, a) of the electromagnetic radiation of the at least two radiation sources (24, 25), wherein during the derivation of the corrected sensor signals ( BR; r 1), at least one linear combination is formed from components of the sensor signals ( BR; r 1) assigned to the different radiation sources (24, 25) (R k), wherein the at least one spectral property (a k, a) of the electromagnetic radiation of the radiation source (24, 25) is given by at least one parameter ( a k, a) which characterizes one or more spectral parts of the electromagnetic radiation of the radiation source (24, 25), and wherein at least one first parameter (a 1) characterizes the spectral part of a main emission of the electromagnetic radiation of the radiation sources (24, 25) and at least one second parameter (a 2) characterizes the spectral part of a secondary emission of the electromagnetic radiation of the radiation sources (24, 25). - at least two radiation sources (24, 25) for emitting electromagnetic radiation by means of which a value document is irradiated, - at least one sensor for detecting the electromagnetic radiation reflected and/or transmitted by the value document and generating corresponding sensor signals, with components ( R k) assigned to the radiation sources (24, 25), wherein the sensor signals are corresponding reflection and/or transmission signals, and - an evaluation device, which is designed to check the value documents on the basis of corrected sensor signals and to derive these corrected sensor signals ( BR; r 1) from the sensor signals taking into account at least one spectral property ( S k ( λ), S ki; a k, a) of the electromagnetic radiation of the at least two radiation sources (24, 25), wherein during the derivation of the corrected sensor signals ( BR; r 1), at least one linear combination is formed from components of the sensor signals ( BR; r 1) assigned to the different radiation sources (24, 25) (R k), wherein the at least one spectral property (a k, a) of the electromagnetic radiation of the radiation source (24, 25) is given by at least one parameter ( a k, a) which characterizes one or more spectral parts of the electromagnetic radiation of the radiation source (24, 25), and wherein at least one first parameter (a 1) characterizes the spectral part of a main emission of the electromagnetic radiation of the radiation sources (24, 25) and at least one second parameter (a 2) characterizes the spectral part of a secondary emission of the electromagnetic radiation of the radiation sources (24, 25). wherein the at least one spectral property (a k, a) of the electromagnetic radiation of the radiation source (24, 25) is given by at least one parameter ( a k, a) which characterizes one or more spectral parts of the electromagnetic radiation of the radiation source (24, 25), and wherein at least one first parameter (a 1) characterizes the spectral part of a main emission of the electromagnetic radiation of the radiation sources (24, 25) and at least one second parameter (a 2) characterizes the spectral part of a secondary emission of the electromagnetic radiation of the radiation sources (24, 25).