An apparatus for diagnosing a state of a battery, comprising: a profile obtaining unit configured to obtain a first profile for voltage and capacity of a battery while the battery is being charged and obtain a second profile for voltage and capacity of the battery while the battery is being discharged; a differential profile converting unit configured to receive the first profile and the second profile from the profile obtaining unit and convert the first profile and the second profile into a first differential profile and a second differential profile for voltage and differential capacity of the battery; and a control unit configured to receive the first differential profile and the second differential profile from the differential profile converting unit, determine a first target peak (tp11, tp21) among a plurality of peaks included in the first differential profile, diagnose a first state of the battery according to a comparison result between the determined first target peak and a preset first reference peak, determine a second target peak (tp12, tp22) among a plurality of peaks included in the second differential profile, diagnose a second state of the battery according to a comparison result between the determined second target peak and a preset second reference peak, and diagnose a state of the battery by using at least one of the diagnosed first state and the diagnosed second state, wherein the first target peak of the first differential profile and the second target peak of the second differential profile are configured to correspond to each other, wherein the control unit is configured to: diagnose the first state as a pending state or a negative electrode degraded state, wherein the pending state is a state in which the control unit reserves the determination of the battery state, and diagnose the second state as any one of a normal state, a positive electrode degraded state and a negative electrode degraded state. a profile obtaining unit configured to obtain a first profile for voltage and capacity of a battery while the battery is being charged and obtain a second profile for voltage and capacity of the battery while the battery is being discharged; a differential profile converting unit configured to receive the first profile and the second profile from the profile obtaining unit and convert the first profile and the second profile into a first differential profile and a second differential profile for voltage and differential capacity of the battery; and a control unit configured to receive the first differential profile and the second differential profile from the differential profile converting unit, determine a first target peak (tp11, tp21) among a plurality of peaks included in the first differential profile, diagnose a first state of the battery according to a comparison result between the determined first target peak and a preset first reference peak, determine a second target peak (tp12, tp22) among a plurality of peaks included in the second differential profile, diagnose a second state of the battery according to a comparison result between the determined second target peak and a preset second reference peak, and diagnose a state of the battery by using at least one of the diagnosed first state and the diagnosed second state, wherein the first target peak of the first differential profile and the second target peak of the second differential profile are configured to correspond to each other, wherein the control unit is configured to: diagnose the first state as a pending state or a negative electrode degraded state, wherein the pending state is a state in which the control unit reserves the determination of the battery state, and diagnose the second state as any one of a normal state, a positive electrode degraded state and a negative electrode degraded state. diagnose the first state as a pending state or a negative electrode degraded state, wherein the pending state is a state in which the control unit reserves the determination of the battery state, and diagnose the second state as any one of a normal state, a positive electrode degraded state and a negative electrode degraded state.