Background: The use of alcohol is increasing from time to time in all segments of demographics and has become one of the rising major public health and socioeconomic problems worldwide. Alcohol use during pregnancy is associated with significant risks to the unborn child and can contribute to prenatal complications. In Ethiopia, there is expansion of alcohol use and have reached to women in their fertile age that include pregnant woman. Objectives: The main objective of this study was to assess the magnitude and associated factors of alcohol use during pregnancy in Kolfe sub city. Methods: Institutional based cross sectional study was conducted from April to June, 2017 in Addis Ababa, Ethiopia. A total of 380 pregnant women were selected by using systematic random sampling and included in the study. Data was collected using questionnaire. The collected data was coded and entered in the computer using Epi Data version 3.1 and the data was analyzed using SPSS for window version 20. Descriptive statistics such as frequency, proportions, means, medians and standard deviations were calculated. A binary logistic regression model was used to identify associated factors for alcohol use among pregnant women. The results were described using adjusted odds ratio with 95% confidence interval and statistical significant was considered at p value < 0.05. Results: This study revealed that the overall prevalence of alcohol use among pregnant women was found to be 39.8%. The factors like not having formal education[AOR 95% CI=8.47(2.42, 29.62), having primary education [AOR 95% CI= 4.26(1.23, 14.74), being housewife[AOR 95% CI= 4.18(2.13,8.22), unplanned pregnancy [AOR 95% CI=2.47(1.33, 4.60), having history of abortion[AOR 95% CI=3.33(1.33, 6.05)], not having awareness on the effect of alcohol on the fetus[AOR 95% CI=4.66(2.53,8.61)], and not having family social support [AOR 95% CI= 2(1.14,3.53) were found to be significantly associated with alcohol use among pregnant women. Conclusions and Recommendations: the study found high level of alcohol use by pregnant women at Kolfe sub city. Not having education, having primary education, being housewife, unplanned pregnancy, having history of abortion, not having awareness on the effect of alcohol on the fetus, and not having family social support are found to be predictors of alcohol use. Factors associated with alcohol use during pregnancy are essential to reduce alcohol use and its health effect.