[Object] To provide a low-cost production method for a heat transportation device with which efficient production with a small number of steps is possible.[Solving Means] A capillary member (5) having a larger thickness than a frame member (2) is mounted on an inner surface (11) of a lower plate member (1). Subsequently, the frame member (2) is mounted on the inner surface (11) of the lower plate member (1), and an upper plate member (3) is mounted on the capillary member (5). Due to a difference between the thickness of the capillary member (5) and the thickness of the frame member (2), a squashing amount (G) is provided between the frame member (2) and the upper plate member (3). Then, the lower plate member (1) and the upper plate member (3) are diffusion-bonded with the frame member (2). At this time, the capillary member (5) is compressed by an amount corresponding to the squashing amount (G). Since the capillary member (5) has elasticity, a pressure (P) is partially absorbed, and a pressure (P′) smaller than the pressure (P) is applied to the lower plate member (1) from the capillary member (5). By the pressure (P′), the inner surface (11) of the lower plate member (1) and the capillary member (5) are diffusion-bonded.