A signal output device, has an output signal generating unit 23 generating the output signals based on the input data, an output control unit 21 outputting the output signals to a reproducing device, a detecting unit 27 which detects missing of the input data, and a substitute data generating unit 28 generating, when the detecting unit 27 detects the missing of the input data, with the exception of a portion with the missing detected, substitute data by averaging at least any one of input data posterior to the missing portion and input data anterior to the missing portion, as data for a period of reproducing time obtained by adding a period of reproducing time related to the input data to a period of reproducing time related to the missing portion, and the output signal generating unit 23 generates the output signals based on the substitute data.