Bone remodeling has important roles in the functions of bone tissues, such as supporting the body and mineral storage. Osteocytes, which are the most abundant cells in bone tissues, detect the mechanical loading and regulate both bone formation by osteoblasts and bone resorption by osteoclasts. However, its mechanism is still unknown. In this review, we summarize how osteocytes detect mechanical stress and discuss the potential role of CCN2/CTGF as a novel bone remodeling factor produced by osteocytes.