A monitor for monitoring an electric storage device comprising: a measurement unit configured to detect a state of the electric storage device and obtain a detected value; a power supply switch portion configured to switch a power supply state of the monitor between a monitoring state and a low power consumption state that requires lower power than the monitoring state; a wakeup timer to which actuation time is set and configured to start counting time in response to switching to the low power consumption state by the power supply switch portion, continue counting time until reaching the actuation time and output an actuation signal if reaching the actuation time; and a memory configured to store a previous detected value that is detected prior to the detected value, wherein: the power supply switch portion switches the power supply state of the monitor from the low power consumption state to the monitoring state every time the wakeup timer outputs the actuation signal, the monitor further comprising: a control unit configured to: control the measurement unit to detect the state of the electric storage device and obtain the detected value when the power supply state of the monitor is set in the monitoring state by the power supply switch portion; characterised in that the control unit is further configured to: obtain a change amount according to comparison between the detected value and the previous detected value; and change the set actuation time according to the change amount. a measurement unit configured to detect a state of the electric storage device and obtain a detected value; a power supply switch portion configured to switch a power supply state of the monitor between a monitoring state and a low power consumption state that requires lower power than the monitoring state; a wakeup timer to which actuation time is set and configured to start counting time in response to switching to the low power consumption state by the power supply switch portion, continue counting time until reaching the actuation time and output an actuation signal if reaching the actuation time; and a memory configured to store a previous detected value that is detected prior to the detected value, wherein: the power supply switch portion switches the power supply state of the monitor from the low power consumption state to the monitoring state every time the wakeup timer outputs the actuation signal, the monitor further comprising: the power supply switch portion switches the power supply state of the monitor from the low power consumption state to the monitoring state every time the wakeup timer outputs the actuation signal, the monitor further comprising: a control unit configured to: control the measurement unit to detect the state of the electric storage device and obtain the detected value when the power supply state of the monitor is set in the monitoring state by the power supply switch portion; control the measurement unit to detect the state of the electric storage device and obtain the detected value when the power supply state of the monitor is set in the monitoring state by the power supply switch portion; obtain a change amount according to comparison between the detected value and the previous detected value; and change the set actuation time according to the change amount.