An object detecting apparatus comprising: a first transmission and reception unit and a second transmission and reception unit each having a transmitter (40a, 40b) configured to emit a transmission wave (Wt1, Wt2) to an area in which an object to be detected may appear, and a receiver (42a, 42b) configured to receive a reflection wave (Wr1, Wr2) reflected from the object when the transmission wave (Wt1, Wt2) is applied to the object: a distance detector configured to detect a distance up to the object based on a delay time (Td) from a time at which the transmitter (40a, 40b) emits the transmission wave (Wt1, Wt2) to a time at which the receiver (42a, 42b) receives the reflection wave (Wr1, Wr2), with respect to each of the first transmission and reception unit and the second transmission and reception unit: and a failure judging section configured to judge whether a failure of the first transmission and reception unit and the second transmission and reception unit has occurred, wherein: an output signal produced from a first receiver, which is the receiver of the first transmission and reception unit, based on the transmission wave that is transmitted directly from a second transmitter, which is the transmitter of the second transmission and reception unit, to the first receiver, is defined as a first output signal; an output signal produced from a second receiver, which is the receiver of the second transmission and reception unit, based on the transmission wave that is transmitted directly from a first transmitter, which is the transmitter of the first transmission and reception unit, to the second receiver, is defined as a second output signal; and using at least one of the first output signal and the second output signal, the failure judging section judges whether a failure of the first transmission and reception unit and the second transmission and reception unit has occurred, and wherein the failure judging section: calculates a first cross-correlation value based on a drive signal supplied to the second transmitter and the first output signal from the first receiver; calculates a second cross-correlation value based on a drive signal supplied to the first transmitter and the second output signal from the second receiver; and judges that a failure has occurred in the first transmission and reception unit or the second transmission and reception unit if a result of a comparison between the calculated first cross-correlation value and the calculated second cross-correlation value does not fall within a normal range. a first transmission and reception unit and a second transmission and reception unit each having a transmitter (40a, 40b) configured to emit a transmission wave (Wt1, Wt2) to an area in which an object to be detected may appear, and a receiver (42a, 42b) configured to receive a reflection wave (Wr1, Wr2) reflected from the object when the transmission wave (Wt1, Wt2) is applied to the object: a distance detector configured to detect a distance up to the object based on a delay time (Td) from a time at which the transmitter (40a, 40b) emits the transmission wave (Wt1, Wt2) to a time at which the receiver (42a, 42b) receives the reflection wave (Wr1, Wr2), with respect to each of the first transmission and reception unit and the second transmission and reception unit: and a distance detector configured to detect a distance up to the object based on a delay time (Td) from a time at which the transmitter (40a, 40b) emits the transmission wave (Wt1, Wt2) to a time at which the receiver (42a, 42b) receives the reflection wave (Wr1, Wr2), a failure judging section configured to judge whether a failure of the first transmission and reception unit and the second transmission and reception unit has occurred, an output signal produced from a first receiver, which is the receiver of the first transmission and reception unit, based on the transmission wave that is transmitted directly from a second transmitter, which is the transmitter of the second transmission and reception unit, to the first receiver, is defined as a first output signal; an output signal produced from a second receiver, which is the receiver of the second transmission and reception unit, based on the transmission wave that is transmitted directly from a first transmitter, calculates a first cross-correlation value based on a drive signal supplied to the second transmitter and the first output signal from the first receiver; calculates a second cross-correlation value based on a drive signal supplied to the first transmitter and the second output signal from the second receiver; and judges that a failure has occurred in the first transmission and reception unit or the second transmission and reception unit if a result of a comparison between the calculated first cross-correlation value and the calculated second cross-correlation value does not fall within a normal range.