We measured somatosensory evoked fields (SEFs) by electric stimulus to the right finger (thumb, fourth, and little finger) using a 39-channel SQUID system. In order to investigate relationship between phase lag and stimulus repetition frequency (SRF), delay time of a component synchronous the SRFs (2.0 to 30.3Hz) was calculated by the convolution of the reference signal and the measured SEF waveform. The phase lag was linear to SRF for at least three different ranges of the SRFs in each SEF data. It was tested for significance of the linear regression slope (β≠0, P<0.05). We also carried out souce estimation with these calculated slopes. Finally, in order to discuss relationship between phase-lag and SRFs, we demonstrated the simulation with the result of the phase lag characteristic.