PURPOSE: To obtain the strength testing method after the reaction of coke characterized by high testing accuracy and high representativeness of a sample under test.

CONSTITUTION: The testing accuracy can be improved by setting the particle size of a sample under test at 15mm or less and/or shortening the reaction time to less than 2 hours and more than 0.5 hour. When the amount of the sample of lump coke is set at 20kg or less, the testing accuracy can be further improved. When the range of the particle size of the sample under test us set at 3mm or more, the yield of the samples is improved, and the representativeness of the sample under test can be enhanced.