Provided is a thermoplastic resin composition comprising 1 to 100 parts by weight of a flame retardant (B) containing any one or more flame retardants (B-1) selected from melamine phosphate, melamine pyrophosphate, and melamine polyphosphate and any one or more flame retardants (B-2) selected from piperazine phosphate, piperazine pyrophosphate, and piperazine polyphosphate, based on 100 parts by weight of a thermoplastic resin (A) comprising polylactide resin, wherein, according to transmission electronic microscopy, the major axis of the largest particle of the flame retardant (B) in the composition is not more than 10 μm, and the ratio of the number of particles of the flame retardant (B) having a major axis of not more than 3 μm relative to the number of particles of the flame retardant (B) per an area of 1,000 μm2 is 70% or more.