You Do Need power plug adapter while traveling from Monaco to Ethiopia.

Here is Why You Need An Adapter

The outlet and plug type used in Ethiopia are C, F and G and in Monaco are C, E and F. This is how they look like.

Monaco

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

Type C

Type E

Type F

Ethiopia

In Ethiopia, outlets of type C, F and G are in use.

Type C

Type F

Type G