IN-SEAT AIRBAG DEVICE

An in-seat airbag device, includes: an airbag main body having a front-rear chamber that, expands past one side of a head of a passenger toward a seat front side and is disposed at the one side of the head of the passenger, a left-right chamber that expands from a seat front side end portion of the front-rear chamber toward a seat width direction inner side and is disposed at a seat front side of a face of the passenger, and a distal end chamber that expands from a seat width direction inner side end portion of the left-right chamber toward a seat rear side and is disposed at another side of the head of the passenger, wherein the airbag main body is structured such that, in a state in which expansion is completed, the left-right chamber has a curved shape as seen in plan view.