Soal olimpiade matematika merupakan jenis soal dalam ranah Higher Order Thinking Skill (HOTS). Di era sekarang peserta didik bukan hanya difokuskan untuk mampu berpikir kritis, tetapi juga harus mempunyai kemampuan literasi yang baik. Kemampuan literasi terkait budaya sekitar sangat diperlukan agar peserta didik dapat mengenal dan melestarikan budaya tersebut. Oleh karena itu, penelitian ini ditujukan untuk; (1) Menghasilkan soal olimpiade matematika jenjang SMP sederajat materi kombinatorika dan peluang terintegrasi kebudayaan lokal Kudus yang valid untuk mengukur tingkat pemahaman peserta didik; (2) Menganalisis kesalahan umum peserta didik dalam menyelesaikan soal yang dikembangkan peneliti. Penelitian ini memakai metode pengembangan dengan model formative research yang meliputi empat tahapan, yakni tahap preliminary, self-evaluation, prototyping, dan field test. Subjek uji coba pada penelitian ini ialah 38 peserta didik SMP 1 Kudus kelas IX, dengan teknik pengumpulan datanya berupa tes tertulis serta wawancara. Hasil penelitian menunjukkan adanya respon yang baik terhadap soal yang dikembangkan peneliti, akan tetapi masih terdapat beberapa kesalahan umum peserta didik dalam menyelesaikan soal tersebut. Berdasarkan hasil penelitian, diperoleh simpulan bahwa: (1) Diperoleh 4 butir soal olimpiade matematika yang dinyatakan valid, dimana nilai V Aiken secara keseluruhan sama dengan 0,8; (2) Kesalahan umum peserta didik saat menyelesaikan soal yang dikembangkan peneliti meliputi kesalahan dalam memahami maksud dari soal, kesalahan dalam memahami rumus, dan kesalahan konsep.AbstractThe math olympiad question is one of the questions in the HOTS domain. In this era, students are not only focused on being able to think critically, but are also required to have good literacy skills. Literacy skills related to surrounding culture are needed so that students can recognize and preserve the culture. Therefore, the existence of this research is intended to; (1) Produce mathematics olympiad questions at the junior high school level equivalent to combinatorics and opportunities integrated with Kudus local culture that are valid to measure the level of understanding of students; (2) Analyzing students' common errors in solving researcher-developed questions. This study uses a development research method with a formative research model consisting of four stages, namely the preliminary, self-evaluation, prototyping, and field test. The test subjects in this study were 38 ninth grade students at SMP 1 Kudus, with data collection techniques in the form of written tests and interviews. The results showed a good response to the problem developed by the researcher, but there were still some common mistakes of students in solving the problem. Based on these results it can be concluded that: (1) There are 4 items of math olympiad questions that are declared valid, where the overall value of V Aiken is equal to 0.8; (2) Common errors of students when solving problems developed by researchers include errors in understanding the meaning of the problem, errors in understanding formulas, and concept errors.