An inertial sensor (1, 1A, 1B), comprising: a detector (4, 4A, 4B) configured to convert an inertial force to an electrical signal; an inertial detection circuit comprising: a signal generator configured to generate a signal to be output to the detector (4, 4A, 4B); and a processing unit configured to process the electrical signal output from the detector (4, 4A, 4B), the detector (4, 4A, 4B) including: a fixed electrode; and a moving electrode disposed to face the fixed electrode, the moving electrode being configured to vibrate with respect to the fixed electrode in a facing direction in which the moving electrode and the fixed electrode face each other and being configured to output the electrical signal corresponding to vibration thereof, the signal generator including: a drive voltage generator configured to apply to the fixed electrode a drive voltage with a first frequency to make the moving electrode vibrate; and a test voltage generator configured to apply to the fixed electrode a test voltage with a second frequency lower than the first frequency to make the moving electrode vibrate, the processing unit including: a detection processor configured to perform a detection processing of detecting a capacitance between the fixed electrode and the moving electrode based on a detection signal of the electrical signal output from the moving electrode, the detection signal corresponding to a component of an inertial force applied to the moving electrode and a diagnostic processor configured to perform a diagnostic processing of diagnosing abnormality of the detector (4, 4A, 4B) based on a diagnostic signal of the electrical signal output from the moving electrode, the diagnostic signal corresponding to a component of the second frequency, the signal generator is configured to correct, based on the diagnostic signal, at least one of an offset or an amplitude of the drive voltage. a detector (4, 4A, 4B) configured to convert an inertial force to an electrical signal; an inertial detection circuit comprising: a signal generator configured to generate a signal to be output to the detector (4, 4A, 4B); and a processing unit configured to process the electrical signal output from the detector (4, 4A, 4B), a signal generator configured to generate a signal to be output to the detector (4, 4A, 4B); and a processing unit configured to process the electrical signal output from the detector (4, 4A, 4B), the detector (4, 4A, 4B) including: a fixed electrode; and a moving electrode disposed to face the fixed electrode, the moving electrode being configured to vibrate with respect to the fixed electrode in a facing direction in which the moving electrode and the fixed electrode face each other and being configured to output the electrical signal corresponding to vibration thereof, a fixed electrode; and a moving electrode disposed to face the fixed electrode, the moving electrode being configured to vibrate with respect to the fixed electrode in a facing direction in which the moving electrode and the fixed electrode face each other and being configured to output the electrical signal corresponding to vibration thereof, the signal generator including: a drive voltage generator configured to apply to the fixed electrode a drive voltage with a first frequency to make the moving electrode vibrate; and a test voltage generator configured to apply to the fixed electrode a test voltage with a second frequency lower than the first frequency to make the moving electrode vibrate, a drive voltage generator configured to apply to the fixed electrode a drive voltage with a first frequency to make the moving electrode vibrate; and a test voltage generator configured to apply to the fixed electrode a test voltage with a second frequency lower than the first frequency to make the moving electrode vibrate, the processing unit including: a detection processor configured to perform a detection processing of detecting a capacitance between the fixed electrode and the moving electrode based on a detection signal of the electrical signal output from the moving electrode, the detection signal corresponding to a component of an inertial force applied to the moving electrode and a diagnostic processor configured to perform a diagnostic processing of diagnosing abnormality of the detector (4, 4A, 4B) based on a diagnostic signal of the electrical signal output from the moving electrode, the diagnostic signal corresponding to a component of the second frequency, a detection processor configured to perform a detection processing of detecting a capacitance between the fixed electrode and the moving electrode based on a detection signal of the electrical signal output from the moving electrode, the detection signal corresponding to a component of an inertial force applied to the moving electrode and a diagnostic processor configured to perform a diagnostic processing of diagnosing abnormality of the detector (4, 4A, 4B) based on a diagnostic signal of the electrical signal output from the moving electrode, the diagnostic signal corresponding to a component of the second frequency, the signal generator is configured to correct, based on the diagnostic signal, at least one of an offset or an amplitude of the drive voltage.