A morphologically controlled three-dimensional (3D) cell construct composed of only cells and having no scaffold material might be a valuable biologic material for tissue engineering applications, as the scaffold materials can cause delay of tissue regeneration in some conditions. To obtain such a 3D cell construct, a 3D thermoresponsive hydrogel (poly-N-isopropylacrylamide) was prepared as a mold material that changes its volume depending on the temperature. Three-dimensional osteoblast cell constructs with a variety of morphologies as well as a monolayered cell sheet were obtained by decreasing the surrounding temperature of the hydrogel designed with a predefined shape and formed by curing in a polymer mold manufactured via 3D printing. The cell sheet or 3D cell constructs detachment resulted from a simple change in the gel volume, not by the surface chemistry of the gel, because the surface hydrophilicity of the gel was maintained over a wide temperature range. These 2D/3D cell constructs have numbers of exciting applications such as cell carriers for tissue regeneration or as model tissues for the biological study.