Transcranial direct current stimulation (tDCS) has considerable potential as a useful method in the field of neurorehabilitation. However, the safety of tDCS for the human is primarily based on theoretical evidence related to electricity, and the safety information of applying tDCS to the human is only available from researcher's reporting. Based on tDCS studies with human and animal subjects and simulation-based studies of the safety of current stimulation in the past 20 years, this review investigated the safety of tDCS application to the human body. No severe complications have been reported in either adults or children for tDCS at an intensity of 4 mA or less, within a period of 60 minutes per day, using commonly applied 25 or 35 cm electrodes. According to animal studies, the amount of electricity used for tDCS is less than 5% of the amount that permanently changes brain tissue, thereby ensuring safety to a certain extent. In order to increase the efficacy of tDCS for neurorehabilitation and to minimize even trivial complications in the human screening of exclusion criteria should be conducted with detailed observations of complications.