[en] We propose a new microcalorimeter in which the critical current of a Josephson junction can be varied by an electron temperature in the normal metal barrier of the superconductor-normal metal-superconductor (SNS) or superconductor-normal metal-insulator-superconductor (SNIS) junctions. In this detector, a Josephson junction with a radiation absorber is included in a superconductor loop and the change of its critical current is converted into a change of magnetic flux in the loop. We estimated the energy resolution of this detector by calculating a noise equivalent power (NEP) of the detector. The estimated energy resolution and dynamic range are 4.2 eV/5.8 eV and 3.1 keV/6.2 keV, respectively with an Ag absorber of 500 x 500 x 2 μm³ at 100 mK