PURPOSE: To obtain a constant amount of delivery of fluid without reference to a circumferential temperature only by operating the value of a resistance in a charge resistance circuit for changing the characteristic of overall resistance freely and selecting the characteristic of resistance of the charge resistance circuit adapted for the characteristic of temperature.

CONSTITUTION: In a drive device for an electromagnetic pump, a charge resistance circuit A is constructed by connecting a heat-sensing element RT and a resistance R7 in parallel and combining this parallel-connected resistance circuit with another resistance R6 in series. In this construction, even if any kind of operation fluid is used for the electromagnetic pump, the characteristic of an overall resistance R can be freely changed and a resistance characteristic of the charge resistance circuit 3A adapted for the characteristic of temperature corresponding to the viscosity of the fluid can be selected only by operating the value of the resistance R7 in accordance with the characteristic of temperature. This construction permits to obtain a constant amount of delivery of the operation fluid easily without reference to a circumferential temperature.