We have investigated the possibility of the phase mode operation, i.e. the mode to transfer the fluxoid, not to transfer the voltage pulse, of Josephson switching system by fabricating a resistively coupled D.C. SQUID's array and 4J-loop which are expected to be advantageous in miniaturization by using its large kinetic momentum effect. The threshold characteristics of these superconducting loops and its LI c dependence agreed with the theoretical predictions. The phase mode logic actions were verified to operate really in a resistively coupled D.C.SQUID's and a coupled D.C. SQUID with a 4J-loop. A computer simulation showed that a resistively coupled SQUID's array acts both on phase mode and voltage mode by changing the circuit parameters, but that the two modes are clearly separated in a parameter space. Finally we have shown a total system configuration of the phase mode operation. For the power loss and the information processing speed, the phase mode was verified to have an advantage over the ordinary voltage mode by two orders of magnitude.