To provide a T-die capable of certainly laminating at least two kinds of thermoplastic resins over the whole in a width direction, and a method for laminating the thermoplastic resins using the T-die.

The T-die 1 is constituted so that at least two kinds of the thermoplastic resins flow in a manifold 16 in a laminated state and flow along the width direction crossing the inflow direction at a right angle to fill the manifold 16 and these resins are discharged from a lip opening part 13 extending along the width direction. In the upstream part on the side of the resin inflow passage 15 of the manifold 16, an expanded part 161 having a predetermined shape is formed on the under side, upper side or both sides thereof over predetermined length in the width direction. In the method for laminating at least two kinds of the thermoplastic resins in the laminated state over the whole in the width direction by the T-die 1, at last two kinds of the thermoplastic resins in the laminated state are passed through the expanded part 161 formed to the manifold 16 to fill the manifold 16 and discharged from the lip opening part 13.