A capsulefor preparing a beverage comprising a lateral wall (2), an inlet wall (3) and an outlet wall (4) forming a hollow body (5) where a brewing product is contained The inlet wall comprises a piercing area, wherein said area is pierced by a brewing device (20)comprising piercing means (21) extending along a predetermined path for perforating said capsule to inject a brewing liquid into the said capsule. The piercing area of the inlet wall (3) comprises at least one portion (10) protruding outside the said inlet wall (3), said portion (10) comprising an inner lateral wall (11), an outer lateral wall (12) and a perforating wall (13).