The resistance of an ideal voltmeter is infinite. An ideal voltmeter is connected in parallel with the component across which the potential difference is to be measured. To ensure that it does not draw current from the circuit and thus does not affect the voltage being measured, the voltmeter must have an extremely high, theoretically infinite resistance. This high resistance prevents current flow through the voltmeter, providing an accurate measurement of the potential difference across the component without altering the circuit conditions. Therefore, the resistance of an ideal voltmeter is infinite to avoid any current draw and interference with the circuit operation.