Over-ear headphone

An over-ear headphone wearable on a user's head, the over-ear headphone comprising:

• a headband;
• two earmuffs, and
• two clamping-force adjusting mechanisms connecting the two earmuffs to two ends of the headband respectively, each clamping-force adjusting mechanism comprising:
• a pivot base connected to the end of the headband, a first side of the pivot base having a first hole structure;
• an adjusting component pivoted to the pivot base and connected to the earmuff;
• a first pin telescopically disposed through the adjusting component to be operably engaged with or disengaged from the first hole structure;
• and
• a first button pressably disposed at the first side of the pivot base, a first protrusion protruding from the first button toward the first hole structure;
• wherein when the first button is pressed, the first protrusion enters the first hole structure to push the first pin out of the first hole structure, for making the adjusting component rotatable to adjust a clamping force of the earmuff upon the user's head;
• when the first button is released, the first pin returns to be engaged with the first hole structure for fixing a pivot angle of the adjusting component relative to the pivot base.