Myofibroblasts proliferate as a result of tension, and they are involved in the development of hypertrophic scars and keloids. Although there is a clear relationship between tension and myofibroblasts, many aspects of the effect of tension on myofibroblast dynamics in completely epithelialized wounds remain unclear. The purpose of this study was to conduct an experimental investigation of the histomorphological effect of different levels of tension applied to wounds following complete epithelialization, on myofibroblast dynamics. Incisions were made in the dorsal skin of 7-week-old, male ICR mice. After the wounds had epithelialized completely, a gauze dressing was applied to mice in the control group, and a hydrocolloid dressing to mice in the intervention group. Tissue samples were prepared on post-incision days 3, 7, 14, and 28, followed by hematoxylin/eosin staining and immunohistochemical staining with anti-αSMA antibodies. Compared with the control group, the width of the wound and the area of granulation tissue both contracted to a significantly greater degree, the fibrous components were more regularly arranged, and myofibroblast regression tended to occur earlier in the intervention group. In the control group, covering the epithelialized wound with a soft material resulted in its exposure to external tension, and this may have caused myofibroblasts to remain in the wound to protect it against this tension. In the intervention group, the applied dressing material relieved the external tension on the epithelialized wound, enabling smooth myofibroblast regression. These results reinforce the recommendation that epithelialized wounds be immobilized until dermal restoration is complete, to prevent hypertrophic scarring.