There is provided a current sensor capable of performing malfunction determination with high accuracy even under the influence of an adscititious magnetic field. A current sensor includes first and second current sensor units, a computation unit, a storage unit, and a determination processing unit. The first current sensor unit measures a target current. The first and second current sensor units have almost the same sensitivity. The computation unit calculates and outputs an addition value and a difference value of outputs of the first and second current sensor units. In the storage unit, the addition and difference values output from the computation unit are stored. The determination processing unit determines whether a malfunction has occurred by using the addition and difference values stored in the storage unit. The determination processing unit determines that a malfunction has occurred, in a case where there is a correlation between the addition and difference values.