A contactless electric power supply device for capacitive power transfer comprising: a contactless electric power supply element provided on a fixed section , a high-frequency power source circuit configured to supply high-frequency electric power to the contactless electric power supply element , a contactless electric power reception element which is facing and separated from the contactless electric power supply element and configured to receive the high-frequency electric power in a contactless manner and which is provided on a movable section that is movably mounted on the fixed section , an electric power reception circuit configured to supply electric power to a current consumer (RL) on the movable section after converting the high-frequency electric power which the contactless electric power reception element received, a contactless transmitting element provided on the movable section , a contactless reception element provided on the fixed section which is facing and separated from the contactless transmitting element and configured to receive electric signals (Sgnl) related to operating condition of the current consumer (RL) in a contactless manner but is not electrically connected to the contactless electric power supply element so that it does not transmit the high-frequency electric power to the contactless transmitting element , and a detection circuit which is provided on the fixed section and that is configured to detect the operating condition of the current consumer (RL), characterized in that the contactless transmitting element is electrically connected to the contactless electric power reception element , and the detection circuit is electrically connected to the contactless reception element , and configured to detect the operating condition of the current consumer (RL) based on the electric signal (Sgnl). a contactless electric power supply element provided on a fixed section , a high-frequency power source circuit configured to supply high-frequency electric power to the contactless electric power supply element , a contactless electric power reception element which is facing and separated from the contactless electric power supply element and configured to receive the high-frequency electric power in a contactless manner and which is provided on a movable section that is movably mounted on the fixed section , an electric power reception circuit configured to supply electric power to a current consumer (RL) on the movable section after converting the high-frequency electric power which the contactless electric power reception element received, a contactless transmitting element provided on the movable section , a contactless reception element provided on the fixed section which is facing and separated from the contactless transmitting element and configured to receive electric signals (Sgnl) related to operating condition of the current consumer (RL) in a contactless manner but is not electrically connected to the contactless electric power supply element so that it does not transmit the high-frequency electric power to the contactless transmitting element , and a detection circuit which is provided on the fixed section and that is configured to detect the operating condition of the current consumer (RL), characterized in that the contactless transmitting element is electrically connected to the contactless electric power reception element , and the detection circuit is electrically connected to the contactless reception element , and configured to detect the operating condition of the current consumer (RL) based on the electric signal (Sgnl). <EOS>