Teaching vocabulary is the most important for young learners because this is the first step in studying an English deeply. Some teachers still face many problems in teaching vocabulary to young learners because young learners had more a special needs rather than adult learners. It is more complicated in teaching vocabulary to young learners. Media that we used is flashcard. Flashcard is one of media in teaching vocabulary that can help teachers in building an active class. Thus, this study to find out the effect of flashcard in teaching vocabulary. This study employed a pre-experimental research design with one group pre-test and post-test conducting 10 questions of multiple choice. Sampling technique used was total sampling, where all populations become a sample. The object of this research consisted of 36 children in the third grade G of MI At Taqwa Bondowoso. The method that was used in this research was quantitative method design. The data were analyzed by using SPSS 21.0. From the analysis data that collected, the score of pre-test was 65.00 and in post-test was 79.44. Furthermore, the result of t-test showed that the significant 2-tailed was 10.277. It can be conclude that there were a significant effect in using a flashcard in teaching vocabulary to young learners.