Diametral impact compression test and impact bending test were carried out using a hammer type impact tester to estimate impact strength of tablets. The hardness, which represents a static compression strength of a tablet, was also determined by the Schleuniger hardness tester. All the tablets used were formulated in the laboratory and, based on weight, thickness, and apparent density, they were classified into five groups. The impact force for breaking 50% of tablets (F₅₀) and the impact tensile strength (σ_I) were used as indices of the impact strength and these values were compared with hardness of the tablet. The data obtained supported following conclusions. 1) It is possible to estimate the impact strength by determining F₅₀, which showed the same tendency as hardness of the tablet. 2) Both the impact and static tensile strengths were proportional to hardness, when the thickness of a tablet was almost the same. 3) Proportional relationship was also suggested between the static and impact tensile strength of the tablet, having almost the same thickness. However, in the case of tablets having similar apparent density and different thickness, the relationship was not observed and the impact tensile strength was almost constant.