In recent years, the target value of slump in general concrete construction is changed from 8 cm to 12 cm in Japan so that constructors will aim to improve workability and ensure quality. However, increasing the concrete slump may cause material separation. As one of the evaluation methods of material separation of fresh concrete, although TAISEI CORPORATION developed a "T-post slump test," this test result depends on the engineers' experience because this test is the qualitative evaluation, not the quantitative evaluation. Therefore, in order to propose the simple evaluation method of this test, we investigate the relationship between the result of the T-post slump test and bleeding amount of fresh concrete in each sand percentage. As a result, it shows that the material separation, which water exudes on the surface, in the T-post slump test occurs at the sand percentage of 40.0% and 50.0% and the final bleeding amount also obtains 0.39 cm3/cm2 and 0.53 cm3/cm2.