Accurate predictive models for gas transport parameters such as the soil-gas diffusion coefficient (D_p) and air permeability (k_a) are important to understand gas transport in soil and predict uptake, production and emission of greenhouse gases such as methane. In spite of this, only limited measurements and knowledge of gas transport parameters in undisturbed peat soil is available. In this study, undisturbed soil core samples were collected from ten depths from a peat soil profile down to 140 cm at the Bibai wetland, Hokkaido, Japan. At three of the 10 depths (30, 60, and 90 cm), intact samples were collected in both vertical and horizontal directions to examine anisotropy in gas transport parameters. The soil cores were saturated and subsequently drained to the desired soil-water potentials (pF = 1.0, 1.5, 1.8, 2.0, 3.0, 4.1, and air-dry), and D_p and k_a were measured at each soil-water potential. Taking the volume decrease with drying into account, volumetric water and air contents were calculated at each potential. Measured Dp and ka were shown as a function of volumetric soil-air content (ε), and the D_p(ε) and k_a(ε) functions were interpreted based on the pore structure characteristics of peat soil materials. The measured D_p and k_a of samples collected in the horizontal direction were larger than those in the vertical direction, and the differences were more enhanced for k_a compared to D_p. Several predictive models for gas transport parameters were also tested against measured data.