Foil bearing and fluid machine

This foil bearing is provided with: a housing; a top foil having a bearing surface facing the rotating body; and a protruding foil disposed between the top foil and the housing. The protruding foil is configured so as to elastically support the top foil by extending in the rotational direction. When the load received by the bearing surface from the rotating body is equal to or less than a threshold value, the protruding foil supports the top foil with a gap between the protruding foil and the housing and with a gap between the protruding foil and the top foil. When the load applied to the bearing surface from the rotating body exceeds the threshold value, the top foil and the protruding foil partially become common bearings to support the rotating body. 本发明的箔片轴承具备：壳体；顶部箔片，其具有与旋转体对置的轴承面；以及凸出箔片，其配置于所述顶部箔片与所述壳体之间。凸出箔片构成为通过沿旋转方向伸长而弹性地支承所述顶部箔片。在所述轴承面从所述旋转体受到的载荷为阈值以下的情况下，所述凸出箔片在与所述壳体之间具有间隙、在与所述顶部箔片之间具有间隙地支承所述顶部箔片。在所述轴承面从所述旋转体受到的载荷超过所述阈值的情况下，所述顶部箔片和所述凸出箔片局部成为普通轴承而支承所述旋转体。