A charging system, comprising: a vehicle to which an electric power storage device is installed, the vehicle being provided with a charging connection portion to which a connector can be connected for charging the electric power storage device; the connector configured to: (a) be attached to and detached from the charging connection portion, and (b) be connected to the charging connection portion in either a fully fitted state and a half-fitted state, charging being able to be performed in the fully fitted state, and the charging being not allowed in the half-fitted state; and a detector configured to detect whether a connecting state of the connector is in the fully fitted state or the half-fitted state; characterized by further comprising an indicator that is an informing portion that is provided in a charging facility and configured to inform a user of abnormal connection of the connector based on a detection result of the detector when the connecting state of the connector is the half-fitted state, wherein the detector is provided in the vehicle and includes an electronic control unit, the detector is configured to detect the connecting state of the connector based on a first signal and a second signal, the first signal and the second signal are provided from the connector through the charging connection portion, the detector is configured to activate the informing portion when either one of the first signal and the second signal indicates the half-fitted state, the first signal is a signal that: (a) indicates presence or absence of the connection of the connector to the charging connection portion and (b) is detected by both of the vehicle and a charging facility, the second signal is a signal that: (a) indicates whether the connecting state of the connector is the fully fitted state or the half-fitted state in addition to the presence or absence of the connection of the connector to the charging connection portion, and (b) is detected by the vehicle but is not detected by the charging facility, and the electronic control unit is configured to transmit a state of the second signal to the charging facility through HLC, PLC or wireless communication after detecting the state of the second signal. a vehicle to which an electric power storage device is installed, the vehicle being provided with a charging connection portion to which a connector can be connected for charging the electric power storage device; the connector configured to: (a) be attached to and detached from the charging connection portion, and (b) be connected to the charging connection portion in either a fully fitted state and a half-fitted state, charging being able to be performed in the fully fitted state, and the charging being not allowed in the half-fitted state; and (a) be attached to and detached from the charging connection portion, and (b) be connected to the charging connection portion in either a fully fitted state and a half-fitted state, charging being able to be performed in the fully fitted state, and the charging being not allowed in the half-fitted state; and a detector configured to detect whether a connecting state of the connector is in the fully fitted state or the half-fitted state; characterized by further comprising an indicator that is an informing portion that is provided in a charging facility and configured to inform a user of abnormal connection of the connector based on a detection result of the detector when the connecting state of the connector is the half-fitted state, wherein the detector is provided in the vehicle and includes an electronic control unit, the detector is configured to detect the connecting state of the connector based on a first signal and a second signal, the first signal and the second signal are provided from the connector through the charging connection portion, the detector is configured to activate the informing portion when either one of the first signal and the second signal indicates the half-fitted state, the first signal is a signal that: (a) indicates presence or absence of the connection of the connector to the charging connection portion and (b) is detected by both of the vehicle and a charging facility, (a) indicates presence or absence of the connection of the connector to the charging connection portion and (b) is detected by both of the vehicle and a charging facility, the second signal is a signal that: (a) indicates whether the connecting state of the connector is the fully fitted state or the half-fitted state in addition to the presence or absence of the connection of the connector to the charging connection portion, and (b) is detected by the vehicle but is not detected by the charging facility, and (a) indicates whether the connecting state of the connector is the fully fitted state or the half-fitted state in addition to the presence or absence of the connection of the connector to the charging connection portion, and (b) is detected by the vehicle but is not detected by the charging facility, and the electronic control unit is configured to transmit a state of the second signal to the charging facility through HLC, PLC or wireless communication after detecting the state of the second signal.