Provided is a modified fibroin, including a domain sequence represented by Formula 1: [(A)n motif-REP]m, in which the domain sequence has an amino acid sequence having a reduced content of (A)n motif equivalent to an amino acid sequence in which, at least, one or a plurality of the (A)n motifs is deleted, as compared to naturally occurring fibroin.
[In Formula 1, (A)n motif represents an amino acid sequence consisting of 4 to 20 amino acid residues and the number of alanine residues relative to the total number of amino acid residues in the (A)n motif is 83% or more, REP represents an amino acid sequence consisting of 10 to 200 amino acid residues, m represents an integer of 8 to 300, and a plurality of (A)n motifs or the like may be the same amino acid sequence or different amino acid sequences.]