[Problem] To calculate power consumption with high accuracy at a jack portion in a power strip and in a power measurement method. [Solving Means] The problem is solved by a power strip including: a second power line 12 between which and a first power line 11 a power supply voltage is applied; a jack portion 1a; a current meter 30 configured to measure a current being supplied to an external electrical device from the jack portion 1a; a first photocoupler 41 including a first light emitting diode 41a connected between the first power line 11 and the second power line 12 and configured to output a first output signal S 1 whose level is changed when the power supply voltage exceeds a first threshold V 1 ; and a computing unit 33 configured to calculate a power value by using instantaneous values I(t) of the current measured by the current meter 30 and instantaneous values V(t) of the power supply voltage estimated from the length X 0 of a period when the level of the first output signal S 1 is changed.
