There is provided a sensor testing method including: applying at least one of a first voltage that obtains a response caused by a substance and a second voltage that either obtains no response or substantially no response caused by the substance across a first electrode and a second electrode of a sensor; measuring current flowing between the first electrode and the second electrode; and determining whether or not there is a defect present in the sensor based on a quantity related to an amount of change per specific period of time of a current measured when the first voltage and/or the second voltage have been applied.