1. A diagnosis device for energy transfer in a vehicle, comprising: an input energy computation means for determining an input energy of the energy transfer system of the vehicle; an output energy computation means for determining an output energy of the energy transfer system; and a comparing means for comparing the input energy determined by the input energy computation means with the output energy determined by the output energy computation means, wherein any anomaly in the energy transfer system is determined based on the result of comparison by the comparing means.