A power measuring system, a measuring apparatus, a load terminal, and a device control system are provided. A voltage sensor detects a voltage waveform, and a current sensor acquires a current waveform, of a power line in a noncontact manner. A load terminal operates to connect the power line and a voltage measuring terminal to measure a current flowing from the power line to a load and to calculate a voltage value from the measured current value and the load. The load terminal transmits, in response to a request from a measuring apparatus, the measured current value and the calculated voltage value to the measuring apparatus via a communication means. A control portion of the measuring apparatus receives the current value and the voltage value from the load terminal. The control portion calculates a power value based on the received current value, voltage value voltage waveform and current waveform.