Siswa sekolah dasar harus dimunculkan kemampuannya untuk berpikir kreatif, supaya siswa mampu memecahkan masalah dengan atau ide-ide atau gagasan kreatif. Dipilih satu pendekatan pembelajaran matematika dengan open-ended berstrategi n-omino untuk memunculkan dan membangun kemampuan siswa berpikir kreatif. Metode kuasi eksperimen dalam penelitian yang rancangannya nonequivalent control group design. Siswa kelas IV SDN di Kecamatan Beber Kabupaten Cirebon sebagai wilayah generalisasi penelitian. Dipilih dua sampel dengan jumlah anggota sampel 42 siswa untuk kelas eksperimen dan 41 siswa anggota sampel kelas kontrol. Kemudian dikaji pengaruh dari perlakuan pembelajaran matematika di kelas eksperimen dan di kelas kontrol terhadap kemampuan siswa untuk berpikir kreatif matematis. Berdasarkan N-gain, perlakuan pendekatan pembelajaran matematika open-ended berstrategi n-omino dan pendekatan konvensional memiliki persamaan dalam pencapaian dan peningkatan kemampuan matematis siswa berpikir kreatif secara signifikan. Rata-rata prates dan pascates siswa berpikir kreatif di kelas eksperimen lebih unggul dibandingkan kemampuan matematis siswa berpikir kreatif di kelas kontrol.Creative thinking skills can emerge and evolve from the environmental influences and complexity of the problems encountered. Elementary schools, an educational event that is important to equip students to bring up creative thinking skills. Mathematics as an academic in elementary school, bridging students to have a creative mindset. Along with the mathematical creative-thinking skills, there is also an self-efficacy as one of its creative thinking. Mathematics learning with the treatment of an open-ended approach in strategy is examined to know its influence on mathematical creative thinking and student of elementary schools self-efficacy. The research method used is quasi experiment with nonequivalent control group design. The population of research, all students of grade IV SDN in Beber subdistrict. The sample was selected as the experimental class of SDN 1 Wanayasa and as the control class of SDN 2 Sindangkasih. At the level of significance 0,05 can be concluded the open-ended approach in strategy n-omino and conventional approach has a positive influence on the skills of creative thinking mathematical and self-efficacy, open-ended approach strategizing n-omino better in improving the mathematical creative thinking skills and no better in improving self-efficacy of students than conventional approach, there is no relationship between creative thinking ability and self-efficacy in spite of the 3,6% chance that both affects each other. Keywords :Open-Ended Approach, n-Omino Strategy, Mathematical Creative Thinking Ability, Self-Efficacy