A sensor apparatus of the present invention includes a failure diagnosis circuit, and a time point measuring unit for adding the time point information to an output concerning generation of the failure detection signal outputted from the failure diagnosis object section and an output concerning generation of the sense signal such that the output concerning generation of the failure detection signal is made to correspond to the output concerning generation of the sense signal using time point information in terms of time points. In the case of the failure diagnosis circuit determining abnormality of the failure diagnosis object section, the first output terminal outputs the sense signal added with the time point information at the time of occurrence of the abnormality and the sense signal added with the time point information after the time of occurrence of the abnormality, as a signal outside a range of a normal output voltage.