This paper considers the inter-symbol interference mitigating precoder design problem for filtered multi-tone (FMT) systems. In FMT systems, due to the time-domain overlapped impulse response of a prototype filter, the desired channel and the temporal interference, referred to as inter-symbol interference (ISI), channel are linearly dependent, and it is inappropriate to adopt conventional MISO precoding schemes such as zero-forcing and matched-filtering methods. Instead, inspired by the approximate lower-bound equivalence of ISI (from temporally adjacent symbols to the desired symbol) and leakage interference (from the desired symbol to adjacent symbols), we propose a signal-to-leakage-interference-plus-noise ratio maximizing precoder design method to mitigate the ISI. From numerical simulations, it is demonstrated that the proposed precoder design method outperforms existing methods.