There are provided an auxiliary device for mounting nail deformity correction device and a nail deformity correction device mounted on a nail by the same. The auxiliary device includes a resilient block that is placed in parallel with a finger and toe nail in a longitudinal direction of the finger and toe nail, and has elasticity to be elastically contracted and restored in a width direction of the finger and toe nail, and a pair of parallel protrusions that protrudes from an end of the resilient block to be inserted into an inside of the finger and toe nail, and is spaced apart from each other at a predetermined distance in the width direction of the finger and toe nail.
