The invention relates to a thrust reverser (9) for an aircraft nacelle (1), including: a front frame (11), a cowl (21) which can move between an operating position and an intermediate maintenance position downstream of the front frame (11), means (26) for moving the cowl (21) between closed and open positions, and an inner structure (23) which can move between an operating position and an intermediate maintenance position downstream of the front frame (11). In addition, the cowl (21) comprises two half-cowls (21a, 21b) and the inner structure (23) comprises two structure halves (23a, 23b), whereby said half-cowls (21a, 21b) and said inner structure halves (23a, 23b) can open outward when the cowl (21) and the inner structure (23) are in the intermediate maintenance position.