This study is designed to comprehend the birth of Vietnamese modern poetry, ‘tho moi’(it means ‘new poetry’). For this, I assume that there are three main literary requisites for birth of ‘tho moi’. First, Vietnamese people have made great much of verse. In the middle age, the greater part of literary works in Vietnamese were written in verse. Second, writers who hoped to reform the traditional verse were against following rules of versification, especially using rhyming. Third, French romanticism overwhelmed the literary world. For Vietnamese people having made great much of verse, it was unfamiliar for them to imagine some free verse. On the other hand some writers tried to abolish all limitations in the medieval poetry. So it was able to forsee discontinuity in the growth of modern poetry. But as French poetry played go-between role, ‘tho moi’ could keep the balance. French poetry used 8, 10, 12 syllables and also used rhyming. By internalizing the influences of French versification, the writers of ‘tho moi’ could harmonize the old and the new, the Orient and the Occident. In conclusion the three main literary requisites I assumed above had co-operated positively in the making of ‘tho moi’.