PURPOSE: To prevent the leakage of a sample in a sample box by inserting the measuring part of a moisture meter into the sample in the box through the sample receiving port of the sample box.

CONSTITUTION: When a linear motor is driven and the shaft thereof 14A begins to advance, a sample box 3 is received gradually into a drying chamber 2 in accordance with the advance of the shaft 14A. In the case of this reception, the rear part of the sample box 3 is abutted against an operating rod 28 whereby the operating rod 28 is lifted against a spring 27 while being rotated counterclockwise about a rotating axis 26. Further, the measuring electrode 30 of a moisture meter 29 is descended in conjunction with the movement of the operating rod 28 while being rotated counterclockwise about the rotating axis 26 and is inserted forcibly into a sample through the sample receiving port of the sample box 3.