A vehicle side section structure comprising: a door outer panel that is configured to be a vehicle width direction outer side portion of a side door; an airbag that is capable of being inflated and deployed toward a vehicle width direction outer side of the side door by gas ejected due to actuation of an inflator; a controller including a prediction section that is configured to predict whether or not an object approaching the vehicle will collide with the side door, the controller being configured to actuate the inflator when it has been determined that the object will collide with the side door based on a signal output from the prediction section; a reinforcement member (48, 60, 70, 80, 90); the vehicle side section structure being characterized by further comprising: a door inner panel that is configured to be a vehicle width direction inner side portion of the side door; an airbag inflation portion that is normally closed off, the airbag inflation portion being provided to the door outer panel such that the airbag is capable of being inflated and deployed to the vehicle width direction outer side of the door outer panel by passing through an opening of the door outer panel when the airbag is inflated and deployed; wherein the reinforcement member (48, 60, 70, 80, 90) is disposed at the vehicle width direction inner side of the inflator, includes a support portion (48C, 60A, 70A, 80A, 92A) supporting the inflator, and is attached to the door inner panel; the inflator is disposed between the door outer panel and the door inner panel; the airbag inflation portion is covered by a door outer molding disposed on the opening of the door outer panel, the door outer molding being configured including a cover portion that covers the opening and a plurality of pairs of anchor portions that anchor to the opening, the respective pairs of the plurality of anchor portions have corresponding pairs of inclined face portions (54B1,54B2) that are located opposite to the cover portion with each of the pairs of inclined face portions (54B1,54B2) being inclined in different directions, wherein each inclined face portion (54B1) is inclined in a direction such that the width of the anchor portions in the transverse direction of the cover portion increases on progression toward the opposite side of the anchor portions to that of the cover portion and each inclined face portion (54B2) is inclined in a direction such that the width of the anchor portions increases on progression toward the cover portion side of the anchor portions, and the door outer molding being configured so as to be separable from the door outer panel when pressed by the airbag. a door outer panel that is configured to be a vehicle width direction outer side portion of a side door; an airbag that is capable of being inflated and deployed toward a vehicle width direction outer side of the side door by gas ejected due to actuation of an inflator; a controller including a prediction section that is configured to predict whether or not an object approaching the vehicle will collide with the side door, the controller being configured to actuate the inflator when it has been determined that the object will collide with the side door based on a signal output from the prediction section; a reinforcement member (48, 60, 70, 80, 90); a door inner panel that is configured to be a vehicle width direction inner side portion of the side door; an airbag inflation portion that is normally closed off, the airbag inflation portion being provided to the door outer panel such that the airbag is capable of being inflated and deployed to the vehicle width direction outer side of the door outer panel by passing through an opening of the door outer panel when the airbag is inflated and deployed; wherein the reinforcement member (48, 60, 70, 80, 90) is disposed at the vehicle width direction inner side of the inflator, includes a support portion (48C, 60A, 70A, 80A, 92A) supporting the inflator, and is attached to the door inner panel; the inflator is disposed between the door outer panel and the door inner panel; the airbag inflation portion is covered by a door outer molding disposed on the opening of the door outer panel, the door outer molding being configured including a cover portion that covers the opening and a plurality of pairs of anchor portions that anchor to the opening, the respective pairs of the plurality of anchor portions have corresponding pairs of inclined face portions (54B1,54B2) that are located opposite to the cover portion with each of the pairs of inclined face portions (54B1,54B2) being inclined in different directions, wherein each inclined face portion (54B1) is inclined in a direction such that the width of the anchor portions in the transverse direction of the cover portion increases on progression toward the opposite side of the anchor portions to that of the cover portion and each inclined face portion (54B2) is inclined in a direction such that the width of the anchor portions increases on progression toward the cover portion side of the anchor portions, and the door outer molding being configured so as to be separable from the door outer panel when pressed by the airbag.