A vehicle side portion structure comprising: a pair of rockers that, at vehicle side portions, respectively extend along a vehicle longitudinal direction at both outer sides in a vehicle transverse direction of a floor panel that is a floor portion of a vehicle cabin interior, first impact absorbing portions (52, 54) that form closed cross-sectional structures and that are configured to, at a time of a side collision of a vehicle, plastically deform and absorb collision energy being provided at interiors of the pair of rockers; and side doors that open and close door opening portions of the vehicle side portions, second impact absorbing portions, which form closed cross-sectional structures and are configured to, at the time of a side collision of the vehicle, plastically deform and absorb collision energy, being provided at lower portions of interiors of the side doors, wherein, in a vehicle side view, the first impact absorbing portions (52, 54) and the second impact absorbing portions are provided so as to overlap with one another, wherein each first impact absorbing portion (52, 54) includes a first upper wall (52A, 54A), a first lower wall (52B, 54B), and first connecting walls (52C, 52D, 54C, 54D, 54E) that respectively connect the first upper wall (52A, 54A) and the first lower wall (52B, 54B), the first upper wall (52A, 54A), the first lower wall (52B, 54B) and the first connecting walls (52C, 52D, 54C, 54D, 54E) forming first small spaces (56, 58, 60, 62, 64, 66, 68), and wherein each second impact absorbing portion includes a second inner wall, a second outer wall, and three second connecting walls (78F, 78G, 78H) that respectively connect the second inner wall and the second outer wall, the second inner wall, the second outer wall and the second connecting walls (78F, 78G, 78H) forming second small spaces (80, 82, 84, 86), characterized in that the three second connecting walls (78F, 78G, 78H), the first upper walls (52A, 54A) and one of the first lower walls (52B, 54B) are horizontal, extend in the vehicle transverse direction, and are provided in succession along the vehicle transverse direction with the ridgelines thereof being lined-up in a state of overlapping in a vehicle height direction. a pair of rockers that, at vehicle side portions, respectively extend along a vehicle longitudinal direction at both outer sides in a vehicle transverse direction of a floor panel that is a floor portion of a vehicle cabin interior, first impact absorbing portions (52, 54) that form closed cross-sectional structures and that are configured to, at a time of a side collision of a vehicle, plastically deform and absorb collision energy being provided at interiors of the pair of rockers; and side doors that open and close door opening portions of the vehicle side portions, second impact absorbing portions, which form closed cross-sectional structures and are configured to, at the time of a side collision of the vehicle, plastically deform and absorb collision energy, being provided at lower portions of interiors of the side doors, wherein, in a vehicle side view, the first impact absorbing portions (52, 54) and the second impact absorbing portions are provided so as to overlap with one another, wherein each first impact absorbing portion (52, 54) includes a first upper wall (52A, 54A), a first lower wall (52B, 54B), and first connecting walls (52C, 52D, 54C, 54D, 54E) that respectively connect the first upper wall (52A, 54A) and the first lower wall (52B, 54B), the first upper wall (52A, 54A), the first lower wall (52B, 54B) and the first connecting walls (52C, 52D, 54C, 54D, 54E) forming first small spaces (56, 58, 60, 62, 64, 66, 68), and wherein each second impact absorbing portion includes a second inner wall, a second outer wall, and three second connecting walls (78F, 78G, 78H) that respectively connect the second inner wall and the second outer wall, the second inner wall, the second outer wall and the second connecting walls (78F, 78G, 78H) forming second small spaces (80, 82, 84, 86), characterized in that the three second connecting walls (78F, 78G, 78H), the first upper walls (52A, 54A) and one of the first lower walls (52B, 54B) are horizontal, extend in the vehicle transverse direction, and are provided in succession along the vehicle transverse direction with the ridgelines thereof being lined-up in a state of overlapping in a vehicle height direction.