PURPOSE: To improve the quality of tea product by measuring the water content of the surfaces of tea leaves and the water content of the whole bodies of the tea leaves in a rough tea preparation process, judging whether the processed tea leaves are controlled to a proper water content, and subsequently operating an operation terminal so as to reach the prescribed water content when the measurement result is not a proper value.

CONSTITUTION: The leaves are sampled from respective devices in a rough tea preparation process, and the proper water contents of the tea leaves are measured with surface water content measuring apparatus and total water content measuring apparatus equipped in measuring device. The quality of the rough tea as the product is thereby improved.