1. A method for automatically detecting errors in machine translation using a parallel corpus, comprising: analyzing morphemes of a target language sentence in the parallel corpus and a machine-translated target language sentence, corresponding to a source language sentence, to classify the morphemes into words; aligning by words and decoding, respectively, a group of the source language sentence and the machine-translated target language sentence, and a group of the source language sentence and the target language sentence in the parallel corpus; classifying by types errors in the machine-translated target language sentence by making a comparison, word by word, between the decoded target language sentence in the parallel corpus and the decoded machine-translated target language sentence; and computing error information in the machine-translated target language sentence by examining a frequency of occurrence of said classified error types.