A vehicle rear portion structure comprising: a pair of left and right rear side members that extend along a vehicle longitudinal direction at both sides of a vehicle body rear portion; a rear cross member that connects the pair of left and right rear side members and extends along a vehicle transverse direction, characterized in that it further comprises brackets (40, 62, 72) that have a fixing portion to which a vehicle mounted object is fixed, a first leg portion (44, 74) that extends from the fixing portion toward one side in a vehicle vertical direction and is fixed to the rear cross member, and a second leg portion (46, 48, 78) that extends from the fixing portion toward said one side in the vehicle vertical direction and is fixed to the rear side member, in that the first leg portion (44, 74) comprises: a first mounting portion (44B, 74B) that is fixed to the rear cross member; and a first vertical wall portion (44A, 74A) that connects the first mounting portion and the fixing portion, and in that the second leg portion (46, 48, 78) comprises: a second mounting portion (46B, 48B, 78B) that is fixed to the rear side member; and a second vertical wall portion (46A, 48A, 78A) that connects the second mounting portion and the fixing portion, a first end surface (44X, 74X) at one side in the vehicle longitudinal direction at the first vertical wall portion, and a second end surface (46X, 48X) at another side in the vehicle longitudinal direction at the second vertical wall portion, being inclined in directions of moving away from one another while heading toward said one side in the vehicle vertical direction as seen in a vehicle side view. a pair of left and right rear side members that extend along a vehicle longitudinal direction at both sides of a vehicle body rear portion; a rear cross member that connects the pair of left and right rear side members and extends along a vehicle transverse direction, characterized in that it further comprises brackets (40, 62, 72) that have a fixing portion to which a vehicle mounted object is fixed, a first leg portion (44, 74) that extends from the fixing portion toward one side in a vehicle vertical direction and is fixed to the rear cross member, and a second leg portion (46, 48, 78) that extends from the fixing portion toward said one side in the vehicle vertical direction and is fixed to the rear side member, in that the first leg portion (44, 74) comprises: a first mounting portion (44B, 74B) that is fixed to the rear cross member; and a first vertical wall portion (44A, 74A) that connects the first mounting portion and the fixing portion, and in that a first mounting portion (44B, 74B) that is fixed to the rear cross member; and a first vertical wall portion (44A, 74A) that connects the first mounting portion and the fixing portion, and in that the second leg portion (46, 48, 78) comprises: a second mounting portion (46B, 48B, 78B) that is fixed to the rear side member; and a second vertical wall portion (46A, 48A, 78A) that connects the second mounting portion and the fixing portion, a first end surface (44X, 74X) at one side in the vehicle longitudinal direction at the first vertical wall portion, and a second end surface (46X, 48X) at another side in the vehicle longitudinal direction at the second vertical wall portion, being inclined in directions of moving away from one another while heading toward said one side in the vehicle vertical direction as seen in a vehicle side view. a second mounting portion (46B, 48B, 78B) that is fixed to the rear side member; and a second vertical wall portion (46A, 48A, 78A) that connects the second mounting portion and the fixing portion, a first end surface (44X, 74X) at one side in the vehicle longitudinal direction at the first vertical wall portion, and a second end surface (46X, 48X) at another side in the vehicle longitudinal direction at the second vertical wall portion, being inclined in directions of moving away from one another while heading toward said one side in the vehicle vertical direction as seen in a vehicle side view.