A high-frequency transmission line includes a laminate including dielectric layers, a first signal line provided in the laminate, a second signal line provided in the laminate and positioned on a first side in a direction of lamination relative to the first signal line, so as to cross the first signal line when viewed in a plan view in the direction of lamination, a first ground conductor positioned on a second side in the direction of lamination relative to the first signal line, a second ground conductor positioned on the first side in the direction of lamination relative to the second signal line, and an intermediate ground conductor provided between the first and second signal lines in the direction of lamination, so as to overlap with crossing portions of the first and second lines when viewed in a plan view in the direction of lamination. An area of overlap of the first ground conductor with the first signal line is smaller than an area of overlap of the second ground conductor with the first signal line. An area of overlap of the second ground conductor with the second signal line is smaller than an area of overlap of the first ground conductor with the second signal line.