A switch deterioration detection device comprising: a resistor serially connected with a battery in which charge and discharge are controlled through a switch ; a first differential amplifier configured to amplify a voltage difference between both ends of the switch to output the amplified voltage difference as a first output voltage; a comparator ; a controller configured to determine whether the switch deteriorates based on a compared result of the comparator ; characterized in that : the resistor is serially connected with the battery; the switch deterioration detection device further comprises a second differential amplifier configured to amplify a voltage difference between both ends of the resistor to output the amplified voltage difference as a second output voltage; the comparator is configured to compare levels between the first and second output voltages, and output an output voltage same signal when the first output voltage is the same as the second output voltage as a result of comparing the levels between the first and second output voltages; a calculator configured to calculate a turn-on resistance value of the switch by using the resistance value of the resistor and the amplification ratios of the first and second differential amplifiers when the output voltage same signal is output from the comparator ; and the controller is further configured to determine whether the calculated turn-on resistance value is more than a threshold value, and the controller is configured to control at least one of a resistance value of the resistor and amplification ratios of the first and second differential amplifiers so that the output voltage same signal is output from the comparator . a resistor serially connected with a battery in which charge and discharge are controlled through a switch ; a first differential amplifier configured to amplify a voltage difference between both ends of the switch to output the amplified voltage difference as a first output voltage; a comparator ; a controller configured to determine whether the switch deteriorates based on a compared result of the comparator ; the resistor is serially connected with the battery; the switch deterioration detection device further comprises a second differential amplifier configured to amplify a voltage difference between both ends of the resistor to output the amplified voltage difference as a second output voltage; the comparator is configured to compare levels between the first and second output voltages, and output an output voltage same signal when the first output voltage is the same as the second output voltage as a result of comparing the levels between the first and second output voltages; a calculator configured to calculate a turn-on resistance value of the switch by using the resistance value of the resistor and the amplification ratios of the first and second differential amplifiers when the output voltage same signal is output from the comparator ; and the controller is further configured to determine whether the calculated turn-on resistance value is more than a threshold value, and the controller is configured to control at least one of a resistance value of the resistor and amplification ratios of the first and second differential amplifiers so that the output voltage same signal is output from the comparator . <EOS>