Chair comprising a back rest, two legs (20a, 20b), and a third part comprising two corner pieces (31a, 31b, 31a'), wherein the back rest comprises a first elongated connection member connecting with a first leg of the chair, and a second elongated connection member connecting with a second leg of the chair, wherein the respective elongated connection member (11a, 11b) has an extension from the back rest along a longitudinal direction to a free end (11 a', 11b') of the elongated connection member (11a, 11b), wherein the respective elongated connection member (11a, 11b) is provided with a hole extending along a crossing direction having a main component orthogonal to the longitudinal direction and being provided with an interconnecting portion, wherein the respective leg (20a, 20b) is provided with a first bore extending along the longitudinal direction and a second bore extending along the crossing direction and connecting with the first bore, wherein the first bore is configured to receive a portion of the respective elongated connection member by a relative movement of the elongated connection member along the longitudinal direction into the first bore to such an extent that the hole of the elongated member is in register with the second bore, wherein the respective corner piece (31a, 31a') is provided with a through-going hole or recess being configured to be in register with the hole of the respective elongated member and the second bore of the respective leg (20a, 20b), wherein the chair further comprises a first and a second fastening arrangement each having a head and an elongated part, the respective head directly or indirectly abutting a first side of the respective corner piece, the first side facing away from the respective leg, and the respective elongated part extending through the respective through-going hole or recess and through the second bore and into the hole of the respective elongated connection member, the elongated part having an engaging portion interacting with the interconnecting portion of the hole of the elongated connection member and thereby interconnecting the backrest, the respective leg (20a, 20b) and the respective corner piece (31a, 31b, 31a'), and wherein the respective corner piece (31a, 31b) comprises an abutment portion with one or more abutment surfaces (34a-b) configured to interact with one or more abutment surfaces (24a-b) of an abutment portion of the respective leg (20a, 20b), the abutment portions having an extension along the longitudinal direction and an extension along a direction transverse to the longitudinal direction. wherein the back rest comprises a first elongated connection member connecting with a first leg of the chair, and a second elongated connection member connecting with a second leg of the chair, wherein the respective elongated connection member (11a, 11b) has an extension from the back rest along a longitudinal direction to a free end (11 a', 11b') of the elongated connection member (11a, 11b), wherein the respective elongated connection member (11a, 11b) is provided with a hole extending along a crossing direction having a main component orthogonal to the longitudinal direction and being provided with an interconnecting portion, wherein the respective leg (20a, 20b) is provided with a first bore extending along the longitudinal direction and a second bore extending along the crossing direction and connecting with the first bore, wherein the first bore is configured to receive a portion of the respective elongated connection member by a relative movement of the elongated connection member along the longitudinal direction into the first bore to such an extent that the hole of the elongated member is in register with the second bore, wherein the respective corner piece (31a, 31a') is provided with a through-going hole or recess being configured to be in register with the hole of the respective elongated member and the second bore of the respective leg (20a, 20b), wherein the chair further comprises a first and a second fastening arrangement each having a head and an elongated part, the respective head directly or indirectly abutting a first side of the respective corner piece, the first side facing away from the respective leg, and the respective elongated part extending through the respective through-going hole or recess and through the second bore and into the hole of the respective elongated connection member, the elongated part having an engaging portion interacting with the interconnecting portion of the hole of the elongated connection member and thereby interconnecting the backrest, the respective leg (20a, 20b) and the respective corner piece (31a, 31b, 31a'), and wherein the respective corner piece (31a, 31b) comprises an abutment portion with one or more abutment surfaces (34a-b) configured to interact with one or more abutment surfaces (24a-b) of an abutment portion of the respective leg (20a, 20b), the abutment portions having an extension along the longitudinal direction and an extension along a direction transverse to the longitudinal direction.