You Do Need power plug adapter while traveling from United States of America (US) USA to Nauru.

Here is Why You Need An Adapter

The outlet and plug type used in Nauru is I and in United States of America (US) USA are A and B. This is how they look like.

United States of America (US) USA

In United States of America (US) USA, outlets of type A and B are in use.

Type A

Type B

Nauru

In Nauru, outlets of type I are in use.

Type I