In this paper，a method for estimating the heating efficiency of an induction cooker is proposed. In the cooker，the energy is transferred through the two processes from the coil to the water in the pan. In the first process，magnetic energy is transferred from the coil to the pan. In the second process，heat is transferred from the pan to the water. Copper loss occurs in the first process，and heat loss to the air and other materials occurs in the second process. We estimated the heat value in the pan and the losses in the coil and the aluminum ring using the 3D finite element method for eddy current problems. Next，we estimated the heat quantity transferred to the water and thus the heating efficiency using the 3D finite element method for heat transfer problems. The estimated results for the heat value in the pan，the losses，the time variation of the water temperature and the heating efficiency were validated by experimental results.