In an effort to make a functional and stable yogurt, this study investigated the improvement effects of sea tangle extract and sea tangle yogurt on intestinal function. The intestinal improvement effect of the extract was measured by the charcoal meal transit method, employing Balb/C mice. And constipation relief was compared utilizing the loperamide-induced constipation method, employing SD rats. Charcoal meal transit was remarkably increased in the mice receiving sea tangle extract as compared to the controls. The constipation relief effects of the sea tangle and sea tangle yogurt were evaluated by measuring fecal amounts in the rats after adding them to water. The fecal contents increased remarkably in the sea tangle administered rat groups as compared to the control group. In addition, different yogurt samples were used to evaluate the characteristics of the sea tangle yogurt. During storage, pH slightly decreased in the yogurt with sea tangle as well as without. At the same time, acidity slowly increased as the storage duration increased. As time elapsed, the amounts of viable cells increased in both yogurts (with and without sea tangle). In the sensory evaluation, significant differences were shown between the sea tangle yogurt and the control for color, flavor, sweetness, and overall quality. Overall, based on the combined results of the intestinal function effects and sensory evaluation, the 0.25% sea tangle yogurt proved to be superior.