A charger having a battery diagnosis function, wherein the charger is connected between an input power supply supplying an input voltage and a battery and charges the battery with the input voltage, the charger comprising: a full-bridge-circuit connected to the input power supply and comprising a first switch (S 1), a second switch (S 2), a third switch (S 3), and a fourth switch (S 4) to generate an alternating current flow; a transformer comprising a primary winding (N P) and a secondary winding (N S1, N S2), wherein the primary winding (N P) is connected to the full-bridge-circuit to transform the input voltage received from the full-bridge-circuit and transmits the voltage to the secondary winding (N S1, N S2); and a rectifying circuit comprising a fifth switch (S 5) and a sixth switch (S 6), connected between the secondary winding (N S1, N S2) and the battery, and rectifying the voltage received from the transformer to charge the battery, or transmitting power in two directions for diagnosing a state-of-health of the battery, wherein the rectifying circuit comprises: the sixth switch (S 6) connected to one end of the secondary winding (N S1, N S2); and the fifth switch (S 5) connected to the other end of the secondary winding (N S1, N S2), characterized in that the charger further comprises: a controller controlling the first (S 1), the second (S 2), the third (S 3), the fourth (S 4), the fifth (S 5), and the sixth (S 6) switches to charge the battery with the input voltage or applying a perturbation voltage for diagnosing the state-of-health of the battery, and diagnosing the state-of-health of the battery based on a response current output from the battery in response to the perturbation voltage, wherein the perturbation voltage is generated by transmitting, by operating the first to sixth switch, power generated in the second winding (N S1, N S2) to the battery. a full-bridge-circuit connected to the input power supply and comprising a first switch (S 1), a second switch (S 2), a third switch (S 3), and a fourth switch (S 4) to generate an alternating current flow; a transformer comprising a primary winding (N P) and a secondary winding (N S1, N S2), wherein the primary winding (N P) is connected to the full-bridge-circuit to transform the input voltage received from the full-bridge-circuit and transmits the voltage to the secondary winding (N S1, N S2); and a rectifying circuit comprising a fifth switch (S 5) and a sixth switch (S 6), connected between the secondary winding (N S1, N S2) and the battery, and rectifying the voltage received from the transformer to charge the battery, or transmitting power in two directions for diagnosing a state-of-health of the battery, wherein the rectifying circuit comprises: the sixth switch (S 6) connected to one end of the secondary winding (N S1, N S2); and the fifth switch (S 5) connected to the other end of the secondary winding (N S1, N S2), the sixth switch (S 6) connected to one end of the secondary winding (N S1, N S2); and the fifth switch (S 5) connected to the other end of the secondary winding (N S1, N S2), characterized in that the charger further comprises: a controller controlling the first (S 1), the second (S 2), the third (S 3), the fourth (S 4), the fifth (S 5), and the sixth (S 6) switches to charge the battery with the input voltage or applying a perturbation voltage for diagnosing the state-of-health of the battery, and diagnosing the state-of-health of the battery based on a response current output from the battery in response to the perturbation voltage, wherein the perturbation voltage is generated by transmitting, by operating the first to sixth switch, power generated in the second winding (N S1, N S2) to the battery. a controller controlling the first (S 1), the second (S 2), the third (S 3), the fourth (S 4), the fifth (S 5), and the sixth (S 6) switches to charge the battery with the input voltage or applying a perturbation voltage for diagnosing the state-of-health of the battery, and diagnosing the state-of-health of the battery based on a response current output from the battery in response to the perturbation voltage, wherein the perturbation voltage is generated by transmitting, by operating the first to sixth switch, power generated in the second winding (N S1, N S2) to the battery.