Refers to matters within a country, organization, or system, often contrasted with 対外 (external/foreign). Common in phrases like 対内政策 (domestic policy) and 対内投資 (inward investment).
The government is reviewing its domestic policies.
Inward direct investment is increasing.
対内 means 'internal, domestic' (as in 対内投資), the direct opposite of 対外 'external, foreign' (as in 対外投資).
inward investment
Compound of 対 (たい, 'toward') and 内 (ない, 'inside'). The combination yields the meaning 'inward' or 'domestic'.