To provide a lower vehicle body structure for a slide door vehicle capable of simplifying forming and assembling work and improving formability and ease of assembling work without deteriorating sealing performance between a floor panel and a side sill, even when a swelling part swelling to inside of a vehicle is provided in a side sill inner, in the lower vehicle body structure for the slide door vehicle having slide side doors.

As shown in the Fig. 7, the floor panel 9 constitutes a cabin floor by joining an outer flange 91 of the floor panel 9 to a joining part 49 positioned in the lower part of the side sill 4, specifically in the lower position of the swelling part 44 of the side sill inner 41 so as to overlap the swelling part 44 with the floor panel 9 in a plan view.