Proving Equality of Simply Typed Term Rewriting System Chiba et al. (2005, 2006, 2010) proposed a framework of program transformation by templates based on term rewriting. They introduced a notion of correct templates, which guarantee the correctness of transformations for restricted class of term rewriting systems. Since their framework is based on first-order term rewriting, it is hard to apply their method to transform higher-order programs. We propose a new method to prove the equality of simply typed term rewriting systems (STTRSs, for short) as an initial step to extend their framework for higher-order setting. We modify the notion of equivalent transformation of STTRSs and give sufficient conditions to guarantee the equality of STTRSs based on the notion of equivalent transformation.