To provide both a high-strength flame-resistant fiber nonwoven fabric having excellent flame resistance, uniformity and abrasion resistance in spite of a low weight and a method for producing the same.

This flame-resistant staple fiber nonwoven fabric is obtained as follows. Flame-resistant staple fibers having ≥45 limiting oxygen index are mixed with flame-retardant staple fibers so as to provide (60/40) to (95/5) weight ratio thereof and a web is formed. The resultant web is subjected to a columnar stream treatment to entangle the flame-resistant staple fibers with the flame-retardant staple fibers.