It is found that an antisense oligonucleotide comprising a sequence complementary to a sequence lying between position-95 and position-109, position-176 and position-192, position-467 and position-484, position-940 and position-954, position-1017 and position-1032, position-1102 and position-1116, position-1176 and position-1197, position-1222 and position-1236, position-1727 and position-1743, position-1858 and position-1873, position-1946 and position-1960, position-2294 and position-2308, position-2360 and position-2377, position-2449 and position-2469, position-2605 and position-2624, position-2689 and position-2703, position-2950 and position-2964, position-3424 and position-3438 or position-3591 and position-3605 in the sequence represented by SEQ ID NO: 2 has an excellent inhibitory activity on the expression of ACSL1. A pharmaceutical composition containing the antisense oligonucleotide for ACSL1 according to the present invention as an active ingredient is useful for the prevention or treatment of obesity or type-II diabetes.Linvention concerne un oligonucléotide antisens comprenant une séquence complémentaire à une séquence sétendant entre la position (95) et la position (109), la position (176) et la position (192), la position (467) et la position (484), la position (940) et la position (954), la position (1017) et la position (1032), la position (1102) et la position (1116), la position (1176) et la position (1197), la position (1222) et la position (1236), la position (1727) et la position (1743), la position (1858) et la position (1873), la position (1946) et la position (1960), la position (2294) et la position (2308), la position (2360) et la position (2377), la position (2449) et la position (2469), la position (2605) et la position (2624), la position (2689) et la position (2703), la position (2950) et la position (2964(, la position (3424( et la position (3438) ou la position (3591) et la position (3605) dans la séquence représentée par SEQ ID NO
