The present study investigated whether adult learners of second language (L2) can automatically activate emotional connotation during emotional word recognition as compared native (L1) users and whether L2 use plays a significant role in it. The automaticity of activation was measured through the emotional Stroop task. In this task, emotional words and neutral words were displayed in two different colors, and the participants were asked to indicate the color by button press. Results showed a delay in L2 learners' response to emotional words (the emotional Stroop effect) without significant differences from L1 users' response, indicating comparable automaticity in activating emotional connotation in performing the task. Further analyses on the effect of L2 use revealed its significant role in increasing the emotional Stroop effect. Specifically, L2 learners with higher amount of L2 use in daily life produced a significant emotion Stroop effect comparable to L1 users, while L2 learners with lower L2 use did not. We discuss the importance of L2 use in actual context in automatic processing of L2 emotional words, especially among adult learners who began L2 learning in adulthood in a case of underrepresented languages as L2.