INTRODUCTION Pregnancy is one of the high-risk periods for women's health that the lack of attention to healthy behaviors such as weight control behaviors can lead to adverse consequences on the health of women and also the fetus. Therefore, the aim of this paper was to explore the determinants of weight control self-efficacy among pregnant women using Health Belief Model (HBM). MATERIALS AND METHODS In this cross-sectional study were enrolled 202 pregnant women referring to Health Care Center in Isfahan city, Iran. Sampling method was multistage random. A researcher-made instrument based on HBM structures was used after confirming the valid and reliable. Data were analyzed by software SPSS 21 and descriptive statistics were represented with (frequency, mean and standard deviation) and analytical (Pearson correlation, independent t and liner regression) at the significant level of <0.05. RESULTS The average age of participants was 27.80 ± 5.08. HBM structures were able explained 31% of variance of weight control self-efficacy. Also, of the studied structures, perceived benefits, perceived barriers were statistically significant predictors of weight control self-efficacy, within which perceived barriers (β = 0.391) was the most significant predictor. CONCLUSION The findings of current study showed that the HBM model could be as a suitable framework to identify effective factors for designing educational intervention to improve weight control behaviors among pregnant women.