Plasma etching method and plasma etching apparatus

A plasma etching method for plasma etching a magnetic film containing at least one element selected from the group consisting of Fe, Co and Ni in a processing chamber using a gas containing C element and O element,

• the method comprising:
• etching the magnetic film by a time-modulated plasma;
• and
• supplying a plasma generating gas, that is different from the gas containing C element and O element, to the processing chamber during a period with high amplitude of a time-modulated antenna power,
• wherein a period with low amplitude of the time-modulated antenna power includes a first period, a second period, and a third period,
• the first period is a period in which an electron temperature relaxes, and also is a period in which the gas containing C element and O element is not supplied to the processing chamber,
• the second period is a period in which the gas containing C element and O element is supplied to the processing chamber, and
• the third period is a period in which the gas containing C element and O element is not supplied to the processing chamber.