A thermal analysis device, comprising: two beams extending in the vertical direction, a sample holder assembly detachably attachable to upper ends of the two beams ; a first sample stage and a second sample stage detachably attachable to the upper ends of the two beams instead of the sample holder assembly ; a heater that heats the sample holder assembly or the first sample stage and the second sample stage ; a temperature controller that controls the temperature of the heater ; a temperature measuring section capable of detecting a temperature difference between the upper ends of the two beams ; a weight measuring section that holds the two beams and measures a weight difference between a sample on the first sample stage and a reference substance on the second sample stage ; wherein the sample holder assembly includes: a first sample holder for placing a sample and a second sample holder for placing a reference substance; and a heat sink coupled to each of the first sample holder and the second sample holder with a member having a predetermined thermal resistance; wherein, when the sample holder assembly is mounted on the upper ends of the two beams , the first sample holder and the second sample holder are in contact with the upper ends of the two beams , and wherein the thermal analysis device is designed to measure at least one of the temperature difference and the weight difference while changing the temperature of the heater by the temperature controller . two beams extending in the vertical direction, a sample holder assembly detachably attachable to upper ends of the two beams ; a first sample stage and a second sample stage detachably attachable to the upper ends of the two beams instead of the sample holder assembly ; a heater that heats the sample holder assembly or the first sample stage and the second sample stage ; a temperature controller that controls the temperature of the heater ; a temperature measuring section capable of detecting a temperature difference between the upper ends of the two beams ; a weight measuring section that holds the two beams and measures a weight difference between a sample on the first sample stage and a reference substance on the second sample stage ; wherein the sample holder assembly includes: a first sample holder for placing a sample and a second sample holder for placing a reference substance; and a heat sink coupled to each of the first sample holder and the second sample holder with a member having a predetermined thermal resistance; wherein, when the sample holder assembly is mounted on the upper ends of the two beams , the first sample holder and the second sample holder are in contact with the upper ends of the two beams , and wherein the thermal analysis device is designed to measure at least one of the temperature difference and the weight difference while changing the temperature of the heater by the temperature controller . a first sample holder for placing a sample and a second sample holder for placing a reference substance; and a heat sink coupled to each of the first sample holder and the second sample holder with a member having a predetermined thermal resistance; wherein, when the sample holder assembly is mounted on the upper ends of the two beams , the first sample holder and the second sample holder are in contact with the upper ends of the two beams , and wherein the thermal analysis device is designed to measure at least one of the temperature difference and the weight difference while changing the temperature of the heater by the temperature controller . <EOS>