A rotary machine comprising: a casing having first and second casing half-bodies abutting each other via an abutting surface therebetween, a first flange which is a part of the first casing half-body extending along the abutting surface and in which a first hole portion is formed, and a second flange which is a part of the second casing half-body extending along the abutting surface and in which a second hole portion corresponding to the first hole portion is formed; and a first bolt inserted into the first and second hole portions and fastened to a first female screw (Sf) formed in at least a part of the second hole portion , wherein the first hole portion is passed through the first flange , the second hole portion is formed to be shallower in depth than the thickness of the second flange , the second flange has a first portion (P1) which is thicker than the first flange in a direction in which the second hole portion extends , and the second hole portion is formed in the first portion (P1), characterized in that the second flange has a second portion (P2) which is thinner than the first portion (P1) around the first portion (P1), a third hole portion passing through a portion of the first flange corresponding to the second portion (P2) is formed in the first flange , a fourth hole portion corresponding to the third hole portion , which is shallower in depth than the thickness of the second portion , is formed in the second portion (P2), a second female screw (Sf) being formed in at least a part of the fourth hole portion , the rotary machine further includes a second bolt inserted into the third and fourth hole portions and fastened to the second female screw (Sf), and the first female screw (Sf) is formed at a position deeper than the thickness of the first flange with respect to the abutting surface of the second casing half body . a casing having first and second casing half-bodies abutting each other via an abutting surface therebetween, a first flange which is a part of the first casing half-body extending along the abutting surface and in which a first hole portion is formed, and a second flange which is a part of the second casing half-body extending along the abutting surface and in which a second hole portion corresponding to the first hole portion is formed; and a first bolt inserted into the first and second hole portions and fastened to a first female screw (Sf) formed in at least a part of the second hole portion , wherein the first hole portion is passed through the first flange , the second hole portion is formed to be shallower in depth than the thickness of the second flange , the second flange has a first portion (P1) which is thicker than the first flange in a direction in which the second hole portion extends , and the second hole portion is formed in the first portion (P1), characterized in that the second flange has a second portion (P2) which is thinner than the first portion (P1) around the first portion (P1), a third hole portion passing through a portion of the first flange corresponding to the second portion (P2) is formed in the first flange , a fourth hole portion corresponding to the third hole portion , which is shallower in depth than the thickness of the second portion , is formed in the second portion (P2), a second female screw (Sf) being formed in at least a part of the fourth hole portion , the rotary machine further includes a second bolt inserted into the third and fourth hole portions and fastened to the second female screw (Sf), and the first female screw (Sf) is formed at a position deeper than the thickness of the first flange with respect to the abutting surface of the second casing half body . <EOS>