To provide a resonance-type inverter device which can reduce the number of sensors and hence reduce the cost.

An inverter device has an inverter circuit 2A, a resonance circuit 2B, and a control circuit 3. The inverter circuit has a three-phase main circuit, capacitors C1-C6, and load current sensors Is1-Is3. The resonance circuit has a three-phase auxiliary circuit and an inductor Lr, and the control circuit has a resonance current arrival deciding means 7 and a driving signal generating means 6. The resonance current arrival deciding means has a means 12 detecting a maximum value of absolute value of a load current, a counter set value outputting means 13 which outputs a counter set value corresponding to the maximum value of the absolute value of the load current, and a count operation means 14 which outputs an arrival decision signal after a lapse of time corresponding to the counter set value outputted by the counter set value outputting means since the drive signal generating means outputs a predetermined switching timing signal.