Metallic magnetic calorimeters (MMCs) are one of the most competitive low temperature detector (LTD) readout sensors. They have the advantages of high time resolution, no heat dissipation, and a wide range of operating temperature. We apply MMCs to our neutrinoless double beta decay ($0v{eta}{eta}$) search experiment. A $CaMoO_4$ crystal was employed as both a source of $0v{eta}{eta}$ and an energy absorber. The crystal was thermally connected to a MMC sensor. We set a simple thermal model for this detector and measured pulse shapes are compared with a numerical solution of the thermal model.