A new method for determining the fiber orientation of paper by microwaves makes it possible to determine orientation nondestructively. It allows the orientation angle, the ratio of maximum to minimum intensity of the transmitted microwaves, and the ratio of CD to MD transmitted microwave intensity to be determined in as short a time as 60s. Based on results obtained by mechanical breaking strength and infrared absorption measurements, the direction of the molecular orientation of cellulose chains is reflected in the orientation angle determined by the microwave method. A correlation coefficient of 0.92 was obtained between the orientation angles determined from the angular dependences of the mechanical breaking strength and of microwave attenuation. The apparatus is useful for a quick determination of orientation in various papers. -- AATA