[en] We study the SU(2) string tension using the 36⁴ lattice with a = 0.05 fm in the random multi-instanton configurations with an entire volume of V = (10 fm)⁴. We take the standard instanton-size distribution as ρ^-5 in the infrared region. From about 5 x 10⁶ measurements of Wilson loops, we find the string tension τ .4 GeV/fm in the intermediate region up to 1 fm, when the average instanton size is taken to be ρ-bar = 0.4 fm and the instanton density (N/V)^1/4 = 1/fm. Quantitatively, the string tension strongly depends on the average instanton size as well as the instanton density. We investigate also the clustering of extended monopoles in the maximally abelian (MA) gauge in the multi-instanton ensemble