The present invention provides a signal generating device, a measuring device, an electric leakage detecting device and a signal generating method. Without vector calculation of phase difference, an input current value I, phase-converted current values Icos[theta] Isin[theta] and a stable leakage current are measured easily in short time and are automatically output. The signal generating device according to an embodiment of the invention is characterized in that: through a first comparator and a second comparator, logic signals are respectively generated for voltage waveform and current waveform of a measured circuit and parameters are set; simultaneously full-wave rectification is performed on the current waveform; and a continuous [delta][sigma]ADC is used for performing quantization conversion on the current waveform after full-wave rectification.