This paper, at first, outlined the so far proposed computation methods on horizontal resistance of coupled piles, and then, described the test results of the model coupled piles. The method specified in the Standard Manual of Harbour Structures neglects bending resistance of coupled piles, but the observation in the laboratory made distinct the fact that its component could not be negligible.
　In fact, there is a method which considers its component, but it is rather complicated in the process and difficult in establishing spring constants of individual
piles.
　In this paper the new method is proposed where any modification is not necessary for load-displacement relationships, and the test results verified its reasonableness. From 1st series to 5th series were for the purpose of investigation on the influence of piles conditions on horizontal resistance, and 6th series was aimed to confirm the authenticity of the new method.