An internal combustion engine; comprising a coolant outlet passage, through which a coolant introduced into a water jacket flows from the water jacket toward a radiator; an exhaust gas recirculation pipe through which a portion of the exhaust gas flowing through an exhaust gas passage is recirculated to an intake passage, an exhaust gas cooler that is installed in the internal combustion engine to cool exhaust gas through heat exchange between the exhaust gas flowing through the exhaust gas recirculation passage and the coolant flowing through the coolant outlet passage, wherein the exhaust gas cooler comprises a housing (31, 51, 61) that comprises a support hole (31 h, 61 h), and is configured to be attached to an end of the internal combustion engine and to form the coolant outlet passage; an exhaust gas recirculation pipe (33, 43, 53) that is configured to form a part of the exhaust gas recirculation passage of the internal combustion engine in an inner peripheral side thereof and to be supported by the housing (31, 51, 61) in an outer peripheral side thereof so as to contact the coolant in the coolant outlet passage; further comprising: an expansion joint (35, 45, 55, 65) comprising a generally disc-shaped retaining plate (35a, 45a, 55a, 65a) that expands in a radial direction of the exhaust gas recirculation pipe (33, 43, 53) and is secured to an end of the exhaust gas recirculation pipe; and an annular indented portion (35b, 45b, 55b, 65b) that is integrally formed with the retaining plate (35a, 45a, 55a, 65a), is arranged inside of the support hole (31 h, 61 h) of the housing (31, 51, 61), has cross section curves to make an indented pattern in an expansion/contraction direction around the end of the exhaust gas recirculation pipe (33, 43, 53), and has an annular secured portion that is arranged within the support hole (31 h) and is secured to the generally circular support hole (31 h) by welding in an airtight manner, wherein the retaining plate and the annular indented portion of the expansion joint form a part of the exhaust gas recirculation passage together with the exhaust gas recirculation pipe, and constitute a cylindrical portion that has a bottom in one end thereof and is supported by the support hole (31 h) of the housing, the annular indented portion having at least one fold, an accordion shape in the cross section that curves in a wavelike manner, and an annular bulge shape in its projecting side, wherein the expansion joint (35, 45, 55, 65) is configured to be interposed between the exhaust gas recirculation pipe (33, 43, 53) and the housing (31, 51, 61) to attach the exhaust gas recirculation pipe (33, 43, 53) to the housing (31, 51, 61), wherein the expansion joint elastically deforms to compensate for expansion/contraction of the exhaust gas recirculation pipe (33, 43, 53) when the exhaust gas recirculation pipe (33, 43, 53) expands or contracts with respect to the housing (31, 51, 61). an expansion joint (35, 45, 55, 65) comprising a generally disc-shaped retaining plate (35a, 45a, 55a, 65a) that expands in a radial direction of the exhaust gas recirculation pipe (33, 43, 53) and is secured to an end of the exhaust gas recirculation pipe; and an annular indented portion (35b, 45b, 55b, 65b) that is integrally formed with the retaining plate (35a, 45a, 55a, 65a), is arranged inside of the support hole (31 h, 61 h) of the housing (31, 51, 61), has cross section curves to make an indented pattern in an expansion/contraction direction around the end of the exhaust gas recirculation pipe (33, 43, 53), and has an annular secured portion that is arranged within the support hole (31 h) and is secured to the generally circular support hole (31 h) by welding in an airtight manner, wherein the retaining plate and the annular indented portion of the expansion joint form a part of the exhaust gas recirculation passage together with the exhaust gas recirculation pipe, and constitute a cylindrical portion that has a bottom in one end thereof and is supported by the support hole (31 h) of the housing, the annular indented portion having at least one fold, an accordion shape in the cross section that curves in a wavelike manner, and an annular bulge shape in its projecting side, wherein the expansion joint (35, 45, 55, 65) is configured to be interposed between the exhaust gas recirculation pipe (33, 43, 53) and the housing (31, 51, 61) to attach the exhaust gas recirculation pipe (33, 43, 53) to the housing (31, 51, 61), wherein the expansion joint elastically deforms to compensate for expansion/contraction of the exhaust gas recirculation pipe (33, 43, 53) when the exhaust gas recirculation pipe (33, 43, 53) expands or contracts with respect to the housing (31, 51, 61).