This research aimed to investigate the effect of computers on the test and inter-rater reliability of writing test scores of ESL learners. Writing samples of 20 pen-paper and 20 computer group students were scored in analytic scoring method by two scorers, and then the scores were analyzed in Alpha (Cronbach) model. The results showed that the test and inter-rater reliability of the writing samples of the computer group students were significantly higher than the ones of the pen-paper group participants.