A valuable paper is provided which comprises on a surface of the paper 50 a characteristic pattern 51 detectable by a sensor 16 of a validator 10 to discriminate authenticity of a bill inserted into the validator 10. The bill has at least a distinctive portion detectable by the sensor 16. The paper 50 has its width W substantially same as the width of the bill. The characteristic pattern 51 of the paper 50 is formed on substantially same position in width W as that of the distinctive portion in the bill. The paper 50 is inserted into the validator 10 to detect the characteristic pattern 51 of the paper 50 by the sensor 16 for discrimination of the paper 50 by the validator 10.