Thrust bearing

A thrust bearing disposed so as to face a thrust collar provided on a rotary shaft, the thrust bearing comprising:

• a top foil disposed so as to face the thrust collar;
• a back foil disposed so as to face a surface of the top foil opposite to another surface of the top foil facing the thrust collar, and supporting the top foil;
• and
• an annular plate-shaped base plate disposed on a side of the back foil opposite to the top foil, and supporting the back foil,
• wherein the back foil is formed of back foil pieces arranged in a circumferential direction of the base plate,
• the top foil is formed of top foil pieces disposed on the back foil pieces,
• the base plate includes support areas which support the back foil pieces and which are arranged in the circumferential direction,
• at least one of the support areas includes an inclined surface defined by a first boundary line and by a second boundary line disposed on a trailing side of the first boundary line in a rotational direction of the thrust collar,
• the inclined surface has a height which gradually increases from the first boundary line to the second boundary line, and is formed continuously from the first boundary line to the second boundary line, and
• at least one of the back foil pieces is disposed within the inclined surface.