Plain radiograph, CT, and MRI are still often used to create images of the hand. However, these modalities have the same limitation: their images are all just still images. We, as orthopaedic surgeons, are doctors who examine the motor system such as muscles, bones, tendons, ligaments, and nerves. Therefore, it is very important for us to know about the clinical condition associated with motion. Recent advances in ultrasound devices and digital imaging have been remarkable, and recent high-resolution ultrasound devices have made it possible to create a clear image of superficial structures with a high-frequency probe. It would not be an exaggeration to say that ultrasonography could change the daily orthopaedic medical practice, and it is becoming more and more prevalent in the field of orthopaedics. In the field of hand surgery, most of the region of interest is located within 3 cm under the skin. It means that we could examine most of the region with one high-frequency linear probe. Here, we will present and explain the ultrasonograms from some of the clinical cases we often encounter at our hand clinic. Specifically, we will present cases of tenosynovitis, tendon injury, ligament injury, ganglion cyst, soft tissue tumor, fracture, rheumatoid arthritis, cubital tunnel syndrome, and carpal tunnel syndrome. Ultrasonography is useful not only for diagnosis but also for treatments such as nerve blocks, injections, or punctures. In addition, it is helpful as a communication tool between doctors and patients. In light of this fact, we think it will continue to develop more and more.