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Direct numerical simulation was performed for the spatially advancing turbulent flow in a two-dimensional curved channel. The fully developed turbulence was introduced into the curved channel through a straight part, and observation was made for how the near-wall turbulence advanced along curved walls. The frictional Reynolds number, Reτ0, was fixed at 150, whereas the radius ratio of the curved channel, α, was changed at three steps; 0.8, 0.92, and 0.975. Five computational tests were performed, which include simulations with changing the spanwise length of the channel or the grid arrangement. The maximum number of grid points was 43,610,112 (=936 × 91 × 512) used in the case of α = 0.92. Numerical results for the curved flow were nearly free from the grid arrangement or the spanwise length of the channel, and changes of the mean velocity qualitatively agreed with the experiment by Kobayashi et al. [Trans. Jpn. Soc. Mech. Eng., Ser. B 57, 4064 (1991)], which both supported credibility of the simulation. ...