The present invention relates to a blade (7) comprising: —a composite material structure (17), —a blade root fastening portion (9) further comprising a shoulder (10) extending into the recess from the wall —a base (18) arranged in the recess and comprising a support member configured to abut against the shoulder (10) of the blade root fastening portion (9) and a passage (39) formed in the support member, the sections (23) of the blade root portion (22) of the composite material structure extending through the passage (39), and —a blocking part (19) arranged in the recess between the two sections (23) of the blade root portion (22) such that each section of the blade root portion (23) is pressed against the support member by the blocking part (19).