Due to the formation of numerous translations of the Qur'an and the important role of translation in relation of all sections of society with the teachings of the Holy Qur'an, scholarly criticism of the translations of the Holy Qur'an has emerged as one of the areas of Qur'anic studies in contemporary period. The importance of research in this field is understood when we see translational errors leading to differences in the perceptions of the Qur'an among the general public. Studies of the criticism of the translations of the Qur'an have sought to establish a critical mechanism for evaluating the translations of the Qur'an and hence, it introduces the translators slip places. The present study, through a descriptive and critical analysis, has investigated " Assumming different words as one due to negligence " as one of the slips of the Persian translators of the Holy Qur'an. Enumerating different types of assumming different words as one due to negligence, the two types of " Negligence in diagnosing the root of the words"and “Negligence in pay attention to the differences between similar constructions” have introduced and gave them 12 examples. Statistical reports of translators' performance in the studied samples indicate that translations of Ansarian, Bahrampour, Safavid Mousavi Garmaroudi and Ali Akbar Taheri's have the lowest Negligence. On the other hand, the translations of Mohammad Ebrahim Boroujerdi (9 slips), Mohammad Kazem Arfa (7 slips), Ibrahim Ameli (6 slips), Mohammad Kazem Moezzi (6 slips) have had less success in staying away from Assumming different words as one due to negligence.