You Do Need power plug adapter while traveling from Marshall Islands to Niger.

Here is Why You Need An Adapter

The outlet and plug type used in Niger are C, D, E and F and in Marshall Islands are A and B. This is how they look like.

Marshall Islands

In Marshall Islands, outlets of type A and B are in use.

Type A

Type B

Niger

In Niger, outlets of type C, D, E and F are in use.

Type C

Type D

Type E

Type F