A failure detection device configured to detect a failure of a sound generating device outputting a sound through a speaker based on sound data, wherein the failure detection device comprises: an electronic watermark signal generating means configured to generate an electronic watermark signal including collation data used for collation of whether or not a failure of the sound generating device is detected, wherein the electronic watermark signal generating means is configured to generate the electronic watermark signal by spreading the collation data with a spread code which is generated at random; an addition means configured to add the electronic watermark signal to the sound data output by the sound generating device to generate a stego-signal; the speaker configured to output the stego signal as a sound; a microphone configured to collect the sound output from the speaker; a collation data detection means configured to detect the collation data from the stego-signal, by reversely spreading the stego-signal with the spread code used for generating the electronic watermark signal; a failure determination means configured to determine presence or absence of the failure of the sound generating device, by collating the collation data detected by the collation data detection means, with the collation data included in the electronic watermark signal by the electronic watermark signal generating means; and a second failure detection device configured to electrically detect a failure of the speaker, wherein the failure determination means is further configured to determine presence or absence of a failure of the speaker and the sound generating device, by combining a determination result of the second failure detection device with a determination result of the failure of the sound generating device. an electronic watermark signal generating means configured to generate an electronic watermark signal including collation data used for collation of whether or not a failure of the sound generating device is detected, wherein the electronic watermark signal generating means is configured to generate the electronic watermark signal by spreading the collation data with a spread code which is generated at random; an addition means configured to add the electronic watermark signal to the sound data output by the sound generating device to generate a stego-signal; the speaker configured to output the stego signal as a sound; a microphone configured to collect the sound output from the speaker; a collation data detection means configured to detect the collation data from the stego-signal, by reversely spreading the stego-signal with the spread code used for generating the electronic watermark signal; a failure determination means configured to determine presence or absence of the failure of the sound generating device, by collating the collation data detected by the collation data detection means, with the collation data included in the electronic watermark signal by the electronic watermark signal generating means; and a second failure detection device configured to electrically detect a failure of the speaker, wherein the failure determination means is further configured to determine presence or absence of a failure of the speaker and the sound generating device, by combining a determination result of the second failure detection device with a determination result of the failure of the sound generating device.