Tissue elasticity imaging is a technology for imaging tissue hardness information using ultrasound. We have investigated the use of this method in cases of breast cancer, prostate cancer, etc. [2-4] However, tissue hardness provides important information for many diseases besides breast cancer and prostate cancer. For example, in deep venous thrombosis (DVT), the freshness of a thrombus can be determined from its hardness, and this information is very important for the treatment. However, the hardness of a thrombus that has an anechoic region cannot be measured correctly using conventional methods. Therefore, in this paper, we propose a new tissue elasticity imaging method for disease in anechoic regions. The results of a simulation and a phantom experiment verified that the proposed method is effective for detecting disease in an anechoic region. Moreover, we demonstrate that the proposed method can measure the hardness of a thrombus.