Background: Low Birth Weight (LBW) is an event that makes the infant mortality rate increase in Indonesia. LBW rates in D.I Yogyakarta reached 10% in 2013. Objective: To find out the number of LBW events and find out the relation of the risk factors which was related to the incident at RSKIA Sadewa Sleman in 2016. Method: This is a quantitative research based on analytic observational studies with cross-sectional design. The study sample was 1200 samples consisting of all LBW babies and normal babies born at RSKIA Sadewa Sleman 2016 (January 2016-December 2016). The sampling technique used was purposive sampling. Secondary data from medical records are used to obtain data. This study uses a correlation analysis with Chi Square test. Result: There were 319 LBW events (26.6%) and showed a risk factor that had a significant relationship (p<0.05) with the incidence of LBW with the degree of closeness (r); Mother's age with p= 0,000 (r = 0,373), maternal gestational age with p= 0,000 (r = 0,416), parity with p= 0,000 (r = 0,114), maternal occupation with p= 0,000 (r = 0,112), and pregnancy control (ANC) with p= 0.006 (r = 0.079). The maternal gestational age has the highest closeness of the relationship to the incidence of LBW with a moderate closeness value (r = 0.416). Conclusions: Mother’s age, maternal gestational age, parity, maternal occupation, and pregnancy control (ANC) have a significant relationship to the incidence of LBW and maternal gestational age to be the most closely related factor.