A transmission line includes a laminated insulating body including insulating base material layers that are laminated, signal conductors provided inside the laminated insulating body and extending in a transmission direction along the insulating base material layer, and ground conductors sandwiching the signal conductors in a lamination direction via the insulating base material layers. The transmission line includes at least one curved portion that is bent along a plane orthogonal to the lamination direction. The signal conductors are separated from each other in a direction orthogonal to the transmission direction when viewed in the lamination direction and include a first signal conductor on an inner side and a second signal conductor on an outer side in the curved portion. An interval between the ground conductors sandwiching the first signal conductor is narrower than an interval between the ground conductors sandwiching the second signal conductor.