Tartary buckwheat flour is considered to be a good health food with a new physiological function, because it includes more rutin, an antioxidative component, than the ordinary buckwheat flour. However, by containing rutinase, it has more bitterness than the ordinary buckwheat flour. Therefore, we used the tartary buckwheat flour whose rutinase was deactivated by a heat-moisture treatment in this study, and a series of cookies were made by changing the added amount of the tartary buckwheat flour in order to clarify its optimal ratio as well as its effective use and aptitude from the viewpoints of improving the physical properties, palatability and antioxidative activity of the cookies.<br>  To make each of these sample cookies, 100g of powder, which contains 0, 10, 30, 50 or 70 wt% of the tartary buckwheat flour added to conventional flour, and a certain volume of butter, sugar, and egg, were mixed, molded and baked for 14 minutes at 170°C. Their breaking strengths were measured as the physical property and their volumes were measured by using the rapeseed method. For the appearance evaluation the L^*, a^* and b^* values were measured, and their overall qualities were additionally evaluated by a sensory evaluation. The peroxyl radical scavenging activity was measured by the chemiluminescence method, and the antioxidative activity was compared based on the IC₅₀ value.<br>  As a result, the volume expansion was reduced by adding the tartary buckwheat flour to the cookies, and the rupture stress significantly decreased by adding more than 30 wt% of it. The L^* value decreased, the a^* value rose, and a red color became darken by increasing the added amount of the tartary buckwheat flour. Moreover, the IC₅₀ value decreased and the improvement of the antioxidative activity was observed though the preference of the color decreased. The sample with 50 wt% of the added tartary buckwheat flour was significantly favored in the sensory evaluation.<br>  Consequently, the addition of the tartary buckwheat flour to the cookies was found to be an effective method. It was possible to improve the taste and the texture by adding the tartary buckwheat flour by 50 wt%, and to allow the cookies to have an excellent antioxidative activity.