A leakage current detection device connected between a power source and a load, which includes a self-testing or leakage current detection selection trigger unit, for selecting a leakage current detection mode or a self-testing mode; a self-testing unit, for periodically generating a simulated leakage current signal in the self-testing mode; and a leakage current detection unit, for detecting a leakage current signal in the leakage current detection mode and detecting the simulated leakage current signal in the self-testing mode. The selection trigger unit further causes the power source to be disconnected from the load when a leakage current signal is detected, and sends a self-testing result to the self-testing unit depending on whether the leakage current detection unit detects the simulated leakage current signal. The self-testing unit displays an indication of the self-testing result.