The Spain No.1 has failed to dislodge Diego Lopez from between the sticks since recovering from a broken hand last season and recently admitted he may be forced to think about leaving the Bernebau in search of first-team football.
But his plight has attracted the attention of Buffon, who says Casillas' reaction to the situation is to be applauded.
"I admire him," the Juventus keeper said. "If you consider yourself one of the strongest keepers then it is difficult to accept decisions like these.
"I respect him for how he is behaving during this period."
Buffon has been number one at his club since joining them in 2001, and showed great commitment to the 'Old Lady' of Italian football by staying with them when they were demoted to Serie B in the wake of the match-fixing scandal.
But he admits he suffered depression during the spell without top-flight football.
Buffon continued: "These things happen because we are human. It was difficult to stay for five years without winning and playing Champions League football.
"But winning the Scudetto two years ago gave me and the others who also stayed at the club great pride and happiness. It was incredible."
Juventus travel to the Bernebau on Wednesday to face a side studded with expensive signings. But Buffon says money is no guarantee of results.
He said: "They have signed great players but this does not mean you will win.
"Obviously having the money is a good starting point but you need to achieve the right balance. It needs patience and work."
Real Madrid v Juventus is on Sky Sports 4 on Wednesday night from 7.30pm