Latar Belakang Underweight atau gizi kurang adalah masalah gizi balita yang paling awalbisa terdeteksi dibanding stunting dan wasting. Gangguan awal pertumbuhan anak ditandaidengan weight faltering yaitu berat badan tidak naik sesuai standar, yang jika dibiarkan anakbisa mengalami Underweight, berlanjut menjadi wasting, dan jika dibiarkan akan mengalamistunting. Faktor sosiodemografi dapat mempengaruhi kejadian gizi kurang (underweight) yang tercakup dalam sosiodemografi yaitu tingkat pendidikan ayah, tingka pendidikan ibu, tingkat pengetahuan orang tua, jumlah anggota keluarga dan tingkat pendapatan keluarga. Tujuan: Untuk mengetahui hubungan faktor sosiodemografi dengan kejadian gizi kurang (Underweight) pada balita di wilayah Pesisir Pantai Nipah. Metode: Penelitian ini merupakan penelitian kuantitatif menggunakan studi cross sectional. Populasi penelitian yaitu seluruh orang tua yang memiliki anak balita Di Wilayah Pesisir Pantai Nipah, Kabupaten Lombok Utara, Nusa Tenggara Barat. Teknik pengambilan sampel yang digunakan adalah cluster random sampling. Batas nilai signifikansi adalah p-value <0,05. Hasil: penelitian menunjukkan bahwa tidak terdapat hubungan yang signifikan antara tingkatpendidikan ayah (p-value = 0,794), tingkat pendidikan ibu (p-value = 0,686), dan tingkatpendapatan keluarga (p-value = 0,528) terhadap kejadian gizi kurang. Sedangkan terdapathubungan yang signifikan antara tingkat pengetahuan orang tua (p-value = 0.000) dan jumlah anggota keluarga (p-value = 0,001) terhadap kejadian gizi kurang. Kesimpulan: Berdasarkan hasil uji statistik yang dilakukan, terdapat hubungan antara tingkat pengetahuan orang tua, dan jumlah anggota keluarga terhadap kejadian gizi kurang (underweight) pada balita diwilayah pesisir pantai nipah, sedangkan tidak ditemukan adanya hubungan antara tingkat pendidikan ayah, tingkat pendidikan ibu, dan tingkat pendapatan keluarga terhadap kejadian gizi kurang (underweight) pada balita diwilayah pesisir pantai nipah AbstractBackground: Underweight or insufficient nutrition is a nutritional issue in toddlers that can be detected earlier than stunting and wasting. Early growth disturbances in children are characterized by weight faltering, where the weight does not increase according to standards. If left unaddressed, it can lead to underweight, progress to wasting, and eventually result in stunting. Sociodemographic factors can influence the occurrence of underweight, encompassing educational levels of parents, parental knowledge, family size, and family income. Objective: To determine the relationship between sociodemographic factors and the incidence ofunderweight among toddlers in the Nipah Coastal Area. Method: This research is a quantitative study using a cross-sectional design. The study population consists of all parents with toddlers in the Nipah Coastal Area, North Lombok Regency, West Nusa Tenggara. Cluster random sampling was used to select the sample. The significance level was set at a p-value of <0.05. Results: The study indicates that there is no significant relationship between the father's educationallevel (p-value = 0.794), mother's educational level (p-value = 0.686), and family income (p-value =0.528) with the occurrence of underweight. However, there is a significant relationship between parental knowledge level (p-value = 0.000) and family size (p-value = 0.001) with the occurrence of underweight. Conclusion: Based on the statistical tests conducted, there is a relationship between parental knowledgelevel, and family size with the incidence of underweight in toddlers in the Nipah Coastal Area. Meanwhile, no relationship was found between the father's educational level, mother's educational level, and family income with the occurrence of underweight in toddlers in the Nipah Coastal Area.