consider a battery attach to wire then current flow from positive to negative terminal ,electron having negative charge  ,we know that negative charge is always atract to positive charge,due to negatively charge electron are atract to positive terminal.this is the reason for why does current flow opposite to the direction of motion of electron?
						

							
basically we have two types of conventions of current.
1)electronic current convention
2)conventional current convention
In electronic current convention we consider the flow of electrons alone to decide the direction of current.since we consider electrons here, the direction of current would be along the direction of flow of electrons
 when we talk about the conventional current we consider the flow of protons..that is the direction of flow of protons decide the direction of current.this movement would be opposite to that of electronic movement
 in general we follow the conventional current direction
 your question is about the conventional convention..
 consider a battery in a simple circuit..when you consider the negative terminal..the electrons which are nearby get repelled by this and move towards the positive terminal due to attraction.but since we follow the conventional convention..the direction of current is opposite to that of flow of electrons