The 42-year-old 'Black Friday' director, who is known for making films with real-life issues in the backdrop, said he is an admirer of Hirani.
"I have seen 'PK' and it's one of the most relevant film of today. I really think that Raju Hirani is the bravest filmmaker. He has proved himself twice.
"People say Dibakar (Banerjee), Vishal (Bhardwaj) and I are brave but I feel Raju is the one. He made a film on Gandhiji in 'Lage Raho Munnabhai' and on religion in 'PK' and he did it effectively," Kashyap told.
Kashyap liked the way Hirani dealt with the first half of the Aamir Khan-starrer PK, which released last Friday and is doing good at the box-office.
"PK's first half is amazing and he said everything what he tried to say through the montage. Second half is the story, which you have to tell according to the market and to complete the storyline. Aamir Khan's flashback is the most effective and best part in the film.
"Generally, we filmmakers get into our subject to prove its poignancy so much that we end up making it less effective for audience. But Raju didn't do that," Kashyap said.