Provided is a gas turbine blade capable of improving the heat-conducting capacity of a serpentine channel. In a gas turbine blade (1) including a serpentine channel in which a plurality of cooling channels (12), extending from the base end side to the distal end side of the blade, are provided from the leading edge to the trailing edge of the blade, at least two of these cooling channels (12) being connected in a folded manner at the base end or distal end, the serpentine channel is formed such that the channel cross-sectional area becomes sequentially smaller from the cooling channel (12) provided at the extreme upstream side of the serpentine channel to the cooling channel (12) provided at the extreme downstream side.