Microwave heating device and microwave heating method

A microwave heating device, comprising:

• a heating chamber that accommodates an object to be heated;
• an oscillator part that outputs a signal at an oscillation frequency within a prescribed frequency band;
• a power amplifier part that amplifies power of an output of the oscillator part;
• a power feeding part that supplies an output of the power amplifier part to the heating chamber;
• a power detecting part that detects reflected power reflected from the heating chamber to the power amplifier part via the power feeding part, and supply power supplied from the power amplifier part to the power feeding part, and
• a control part that receives a reflected power signal and a supply power signal from the power detecting part, to control the oscillation frequency of the oscillator part and the output of the power amplifier part, wherein
• prior to start of a heating operation to an object to be heated in the heating chamber, the control part executes a frequency sweep operation of a prescribed frequency band with frequency sweep power being lower than rated supply power being supplied to the power feeding part when the heating operation is performed, to search for minimum reflected power,
• the control part adjusts, in accordance with the minimum reflected power, feeding power to be supplied to the power feeding part when the heating is performed, and
• the control part performs the heating operation at an oscillation frequency that exhibits the minimum reflected power in the frequency sweep operation.