1. A power management apparatus comprising: a power-demand forecasting section configured to forecast a power demand made by an electric-power demander at a future time; a power measurement section configured to acquire a power consumption of said electric-power demander for said time; a demand control section configured to determine a demand for urging said electric-power demander to adjust the amount of electric power consumed by said electric-power demander on the basis of said power demand forecasted by said power-demand forecasting section and said power consumption acquired by said power measurement section; and a demand issuance section configured to issue said demand determined by said demand control section to said electric-power demander.