A shroud assembly of a gas turbine, the shroud assembly being attached to a support to cover an inner peripheral surface of the support, the support being provided at a radially inner side of a casing of the gas turbine along a circumferential direction of the gas turbine, the shroud assembly comprising: a holder provided at the support, a shroud main body which is plate-shaped and includes a main body portion arranged at the radially inner side of the holder, and at least one flange portion projecting from the main body portion in an axial direction and configured to be brought into contact with an axial end portion of an inner peripheral surface of the holder from the radially inner side, characterized in that: the holder includes at least one insertion hole (23a, 24a), the plate-shaped shroud main body includes at least one insertion hole (23a, 24a) formed at the main body portion, the plate-shaped shroud main body is made of a ceramic matrix composite, the shroud assembly further comprises an at least one plate-shaped insertion member including an insertion portion configured to be inserted into the insertion hole (23a,24a) of the shroud main body and the insertion hole (23a, 24a) of the holder, and a head portion configured to, when the insertion portion is inserted into the insertion hole (23a, 24a) of the shroud main body and the insertion hole (23a, 24a) of the holder, be arranged at the radially inner side of the flange portion of the shroud main body to be brought into contact with the flange portion from the radially inner side. the shroud assembly being attached to a support to cover an inner peripheral surface of the support, the support being provided at a radially inner side of a casing of the gas turbine along a circumferential direction of the gas turbine, the shroud assembly comprising: a holder provided at the support, a shroud main body which is plate-shaped and includes a main body portion arranged at the radially inner side of the holder, and at least one flange portion projecting from the main body portion in an axial direction and configured to be brought into contact with an axial end portion of an inner peripheral surface of the holder from the radially inner side, characterized in that: the holder includes at least one insertion hole (23a, 24a), the plate-shaped shroud main body includes at least one insertion hole (23a, 24a) formed at the main body portion, the plate-shaped shroud main body is made of a ceramic matrix composite, the shroud assembly further comprises an at least one plate-shaped insertion member including an insertion portion configured to be inserted into the insertion hole (23a,24a) of the shroud main body and the insertion hole (23a, 24a) of the holder, and a head portion configured to, when the insertion portion is inserted into the insertion hole (23a, 24a) of the shroud main body and the insertion hole (23a, 24a) of the holder, be arranged at the radially inner side of the flange portion of the shroud main body to be brought into contact with the flange portion from the radially inner side. a holder provided at the support, a shroud main body which is plate-shaped and includes a main body portion arranged at the radially inner side of the holder, and at least one flange portion projecting from the main body portion in an axial direction and configured to be brought into contact with an axial end portion of an inner peripheral surface of the holder from the radially inner side, a main body portion arranged at the radially inner side of the holder, and at least one flange portion projecting from the main body portion in an axial direction and configured to be brought into contact with an axial end portion of an inner peripheral surface of the holder from the radially inner side, characterized in that: the holder includes at least one insertion hole (23a, 24a), the plate-shaped shroud main body includes at least one insertion hole (23a, 24a) formed at the main body portion, the plate-shaped shroud main body is made of a ceramic matrix composite, the shroud assembly further comprises an at least one plate-shaped insertion member including an insertion portion configured to be inserted into the insertion hole (23a,24a) of the shroud main body and the insertion hole (23a, 24a) of the holder, and a head portion configured to, when the insertion portion is inserted into the insertion hole (23a, 24a) of the shroud main body and the insertion hole (23a, 24a) of the holder, be arranged at the radially inner side of the flange portion of the shroud main body to be brought into contact with the flange portion from the radially inner side. an insertion portion configured to be inserted into the insertion hole (23a,24a) of the shroud main body and the insertion hole (23a, 24a) of the holder, and a head portion configured to, when the insertion portion is inserted into the insertion hole (23a, 24a) of the shroud main body and the insertion hole (23a, 24a) of the holder, be arranged at the radially inner side of the flange portion of the shroud main body to be brought into contact with the flange portion from the radially inner side.