A magnetic recording medium processing device, comprising: a detection mechanism unit which detects a magnetic recording medium in a card form which is inserted into or discharged from an insertion opening; a pre-head which slides on a magnetic strip (mp) formed on said magnetic recording medium in a card form to read magnetic data; a shutter which is opened/closed according to a detection result of said detection mechanism unit; and a card processing portion which processes magnetic information recorded on said magnetic recording medium in a card form; the magnetic recording medium processing device being characterized in further comprising: a magnetic field generating device which include a magnetic field generating unit for generating a magnetic field by a resonance unit and a drive control circuit for drive-controlling said magnetic field generating unit; wherein said drive control circuit of said magnetic field generating device includes a drive power supply unit for supplying a drive voltage, a reference potential unit and a resonance drive unit for driving said resonance unit; said resonance unit contains a resonance circuit in which an inductor (L1 or L2) and a capacitor (C1 or C2) are connected between a first node and a second node, receives said drive voltage at said first node, and resonates, while said second node is connected to said reference potential unit, to generate a magnetic field; and said resonance drive unit includes a drive switching element which is connected between said second node at said resonance unit and said reference potential unit and is to be switched between a conducting state and a non-conducting state depending on a control signal to switch a connection status of said second node at said resonance unit and said reference potential unit between a connected state and a disconnected state. a detection mechanism unit which detects a magnetic recording medium in a card form which is inserted into or discharged from an insertion opening; a pre-head which slides on a magnetic strip (mp) formed on said magnetic recording medium in a card form to read magnetic data; a shutter which is opened/closed according to a detection result of said detection mechanism unit; and a card processing portion which processes magnetic information recorded on said magnetic recording medium in a card form; the magnetic recording medium processing device being characterized in further comprising: a magnetic field generating device which include a magnetic field generating unit for generating a magnetic field by a resonance unit and a drive control circuit for drive-controlling said magnetic field generating unit; wherein said drive control circuit of said magnetic field generating device includes a drive power supply unit for supplying a drive voltage, a reference potential unit and a resonance drive unit for driving said resonance unit; said resonance unit contains a resonance circuit in which an inductor (L1 or L2) and a capacitor (C1 or C2) are connected between a first node and a second node, receives said drive voltage at said first node, and resonates, while said second node is connected to said reference potential unit, to generate a magnetic field; and said resonance drive unit includes a drive switching element which is connected between said second node at said resonance unit and said reference potential unit and is to be switched between a conducting state and a non-conducting state depending on a control signal to switch a connection status of said second node at said resonance unit and said reference potential unit between a connected state and a disconnected state. a magnetic field generating device which include a magnetic field generating unit for generating a magnetic field by a resonance unit and a drive control circuit for drive-controlling said magnetic field generating unit; wherein said drive control circuit of said magnetic field generating device includes a drive power supply unit for supplying a drive voltage, a reference potential unit and a resonance drive unit for driving said resonance unit; said resonance unit contains a resonance circuit in which an inductor (L1 or L2) and a capacitor (C1 or C2) are connected between a first node and a second node, receives said drive voltage at said first node, and resonates, while said second node is connected to said reference potential unit, to generate a magnetic field; and said resonance drive unit includes a drive switching element which is connected between said second node at said resonance unit and said reference potential unit and is to be switched between a conducting state and a non-conducting state depending on a control signal to switch a connection status of said second node at said resonance unit and said reference potential unit between a connected state and a disconnected state.