This study aims to produce an applicable Sumbawa local wisdom-based mathematics module for elementary school students by using the Four-D (4D) development research design from Thiagarajan. However, the development design of this module only includes three steps, namely define, design, and develop. The product feasibility test is only on the aspect of validity. Observation, interviews, and questionnaires were used to collect the data. The defined stage resulted in the formulation of the material, including the KPK, FPB, Fractions, Two-dimensional Shapes, and three-dimensional Geometry. A draft was created by emerging the elements of Sumbawa local wisdom in the materials, which is then validated at the design stage. The average validation results of material experts were 91.678%, linguists 90%, and media experts were 91.15%. The average validation result of the three specs is 90.94%, categorized as very valid, which confirms that the module is valid and suitable for elementary school students. Penelitian ini bertujuan untuk menghasilkan modul matematika berbasis kearifan lokal Sumbawa yang valid untuk siswa sekolah dasar dengan menggunakan desain penelitian pengembangan Four-D (4D) dari Thiagarajan. Namun, desain pengembangan modul ini hanya meliputi tiga langkah yaitu define, design, dan develop. Pada tahap develop, uji kelayakan produk hanya pada aspek kevalidan. Teknik pengambilan data meliputi observasi, wawancara dan angket. Hasil penelitian pada tahap define yaitu perumusan materi yang meliputi KPK, FPB, pecahan, bangun datar dan bangun ruang. Hasil penelitian pada tahap design yaitu memunculkan unsur kearifan lokal Sumbawa pada materi sehingga menghasilkan draf modul matematika berbasis kearifan lokal Sumbawa untuk divalidasi. Hasil validasi diperoleh bahwa rata-rata hasil validasi ahli materi 91.67%, ahli bahasa 90% dan ahli media 91.15%. Rata-rata hasil validasi ketiga spek yaitu 90.94% dan dikategorikan sangat valid, sehingga dapat disimpulkan bahwa modul matematika berbasis kearifan lokal Sumbawa dikatakan sangat valid dan layak digunakan oleh siswa sekolah dasar.