According to an embodiment, a quantum communication device includes a sift processor, an estimator, a determination unit, and a corrector. The sift processor is configured to acquire sift processing data by referring to a cryptographic key bit string in a predetermined bit string with a reference basis randomly selected from a plurality of bases via a quantum communication channel. The estimator is configured to acquire an estimated error rate of the sift processing data. The determination unit is configured to determine order of the sift processing data in which an error is to be corrected based on the estimated error rate and difference data between a processing speed of error correcting processing and a processing speed of privacy amplification processing. The corrector is configured to acquire one piece of the sift processing data in the order determined by the determination unit, and generate error correcting processing data.