We have developed a new calorimeter for measuring the thermodynamic properties in pulsed magnetic fields. Instrumental design is described along with the instrument construction details, including the sensitivity of a RuO2 thermometer. Operation of the calorimeter is demonstrated by measuring the heat capacity of three samples: pure germanium, CeCu2Ge2, and κ-(BEDT-TTF)2Cu[N(CN)2]Br, in pulsed fields up to 43.5 T. Obtaining field stability is key in measuring high-resolution heat capacity under pulsed fields. We also examine the performance of the calorimeter by employing two measurement techniques: the quasi-adiabatic and dual-slope techniques. We demonstrate that the calorimeter developed in this study is capable of performing high-resolution calorimetry in pulsed magnetic fields, which opens the door to new opportunities for high-field thermodynamic studies.