A peptide nucleic acid derivative represented by Formula I, or a pharmaceutically acceptable salt thereof, for inducing exon skipping within human ACC2 (acetyl-CoA carboxylase 2) pre-mRNA: wherein, n is an integer between 11 and 17; the compound of Formula I possesses at least a 10-mer complementary overlap with the 18-mer pre-mRNA sequence of [(5' → 3') GGCCAUUUCGUCAGUAUC] in the human ACC2 pre-mRNA; the compound of Formula I is fully complementary to exon/intron junction of the human ACC2 pre-mRNA; S 1, S 2, •••, S n-1, S n, T 1, T 2, •••, T n-1, and T n are hydrido radical; X and Y independently represent hydrido or substituted or non-substituted alkyloxycarbonyl radical; Z represents substituted or non-substituted amino radical; B 1, B 2, •••, B n-1, and B n are independently selected from natural nucleobases including adenine, thymine, guanine, cytosine and uracil, and unnatural nucleobases; and, at least four of B 1, B 2, •••, B n-1, and B n are independently selected from unnatural nucleobases represented by Formula II, Formula III, or Formula IV: wherein, R 1, R 2, R 3, R 4, R 5 and R 6 are hydrido radical; L 1, L 2 and L 3 are a covalent linker represented by Formula V covalently linking the basic amino group to the nucleobase moiety: wherein, Q 1 and Q m are substituted or non-substituted methylene (-CH 2 -) radical, and Q m is directly linked to the basic amino group; Q 2, Q 3, •••, and Q m-1 are independently selected from substituted or non-substituted methylene, and oxygen (-O-), radical; and m is an integer between 1 and 15. n is an integer between 11 and 17; the compound of Formula I possesses at least a 10-mer complementary overlap with the 18-mer pre-mRNA sequence of [(5' → 3') GGCCAUUUCGUCAGUAUC] in the human ACC2 pre-mRNA; the compound of Formula I is fully complementary to exon/intron junction of the human ACC2 pre-mRNA; S 1, S 2, •••, S n-1, S n, T 1, T 2, •••, T n-1, and T n are hydrido radical; X and Y independently represent hydrido or substituted or non-substituted alkyloxycarbonyl radical; Z represents substituted or non-substituted amino radical; B 1, B 2, •••, B n-1, and B n are independently selected from natural nucleobases including adenine, thymine, guanine, cytosine and uracil, and unnatural nucleobases; and, at least four of B 1, B 2, •••, B n-1, and B n are independently selected from unnatural nucleobases represented by Formula II, Formula III, or Formula IV: wherein, R 1, R 2, R 3, R 4, R 5 and R 6 are hydrido radical; L 1, L 2 and L 3 are a covalent linker represented by Formula V covalently linking the basic amino group to the nucleobase moiety: wherein, Q 1 and Q m are substituted or non-substituted methylene (-CH 2 -) radical, and Q m is directly linked to the basic amino group; Q 2, Q 3, •••, and Q m-1 are independently selected from substituted or non-substituted methylene, and oxygen (-O-), radical; and m is an integer between 1 and 15. R 1, R 2, R 3, R 4, R 5 and R 6 are hydrido radical; L 1, L 2 and L 3 are a covalent linker represented by Formula V covalently linking the basic amino group to the nucleobase moiety: wherein, Q 1 and Q m are substituted or non-substituted methylene (-CH 2 -) radical, and Q m is directly linked to the basic amino group; Q 2, Q 3, •••, and Q m-1 are independently selected from substituted or non-substituted methylene, and oxygen (-O-), radical; and m is an integer between 1 and 15. Q 1 and Q m are substituted or non-substituted methylene (-CH 2 -) radical, and Q m is directly linked to the basic amino group; Q 2, Q 3, •••, and Q m-1 are independently selected from substituted or non-substituted methylene, and oxygen (-O-), radical; and m is an integer between 1 and 15.