A removal and installation device for external and internal snap rings that can switch between shaft and hole modes by simple operation and produces better controllability, workability, serviceability and easiness in handling is provided. A rotary plate is rotated in a positive direction, a left side lever is turned as a shaft part is rotated integrally with the rotary plate, right and left side levers are crossed substantially in an X shape, the crossed parts supported by the shaft part, realizing the hole mode. The rotary plate is rotated in reverse direction, the left side lever is turned in a reverse direction as the shaft part is rotated in a reverse direction integrally with the rotary plate, both pivot parts of the right and left side levers arranged substantially in a V shape supported by the shaft part so that both projected working tools are parallel, realizing the shaft mode.