Thanks to reply.
Whitout Target bitrate (from BD Preset bitrate 20Mb/s to custom bitrate, 4.5Mb/s) , I didn't change.
Encoder setting are below.
Bitrate buffer: 3MB
VBR buffer initial: 10%
VBR buffer target: 100%
Max I-frame, B-frame, P-frame, Br-frame size: Auto
I-frame interval = 30
Min. I-frame interval = 1
Mark every 1 I-frame as IDR
Fixed I-frame distance: disable
Adaptive B-flame placement: enable
MacroBlock: 8x8
Subpixel search depth: 1/4
Reference frames: 4
Serch range: 99
Weighted prediction for p-frames: enable
Fast intra decision and inter decision: enable
Simplified RD optimaization: enable
Deblocking filter: CABAC
I think this setting is much to Blu-ray standerd.
hmm...