The topic of this talk is set-valued optimization with respect to the set-relations introduced by Kuroiwa, Tanaka and Ha(\cite{K-T-H}). In \cite{S-T-Y-2015}, we have investigated several Ricceri's theorems (\cite{Ric}) related to Fan-Takahashi minimax inequality theorem(\cite{Tak}) for set-valued maps via a certain scalarization method. Fan-Takahashi minimax inequality theorem is one of theorems which give a value of upper bound for minimax value. B.Rcceri exchange a assumprion about images of diagonal, and propose complementary theorem. A stream of set-valued studies by using the scalarization, In 2010, Kuwano, Tanaka and Yamada show us Fan-Takahashi minimax inequality for set-valued maps by using certain scalarizing functions (\cite{K-T-Y-2009}) for sets based on the set-relations. In 2012, Kubo, Tanaka and Yamada propose Ekeland's variational principle for set-valued maps by same method\cite{K-T-Y}. In 2015, we propose a certain Ricceri's theorem on Fan-Takahashi minimax inequality for set-valued maps with respect to the 5th type set-relation\cite{S-T-Y-2015}. In this talk, we introduce an outline of our research on Ricceri's theorems for set-valued maps via scalarization. %