In this research, we propose a Social Learning Management System (SLMS) enabling real-time and reliable feedback for incorrect answers by learners using a social network service (SNS). The proposed system increases the accuracy of learners' assessment results by using a confidence scale and a variety of social feedback that is created and shared through learners' personal SNS connections. The system measures the intimacy between learners and their SNS friends, as well as the registered feedback time for reliable social feedback. We examined the performance of the proposed SLMS in relation to collaborative learning through the measurement of learners' level of satisfaction.