As a powder metallurgy technique, the compression shearing method at room temperature (COSME-RT) is used for making metamagnetic shape memory alloy (MSMA) thin plates. COSME-RT is a method for consolidating a thin plate from powder raw material by a certain dynamic process that simultaneously applies a compression stress and a shearing strain to a powder material at room temperature and in ambient atmosphere. A plate of 50 μm thickness fabricated by COSME-RT using Ni-Co-Mn-In powder from ground sputtered film is cut into 2 × 2 × 0.05 mm3 and then applied to a thermal energy harvesting device. This device generates an average power density of 68 μW cm-3 and a peak power of 0.95 mW cm-3, which makes it possible to supply a small amount of electric power to a certain type of sensor or small sensor device.