Information obtained through sensors and accumulated in wearable computers can be used as big data. To ensure the safety of this information, the security of wearable computers has become more important than ever before. However, the AES that has been widely used cannot be applied to wearable computers due to the size of the embedment area in those devices. Therefore, lightweight ciphers that can be embedded using small areas have begun to be studied. When a cryptographic circuit is used, it is extremely important to examine the measures taken to safeguard against power analysis attack. However, no study has reported on the attack against SIMECK which can be embedded in the smallest-scale circuit among lightweight ciphers. The present study proposes a method for performing power analysis attacks against SIMECK. To our knowledge, this is the first power analysis attack on SIMECK. Experiments using FPGA proved the validity of the proposed method.