Previously, I checked the behavior of PBS for splitting the laser beam into two beam paths.
At that time, the maximum transmitted laser power was 0.4mw, which was too low.

Eventually, it turned out that the PBS was Brewster PBS (see https://www.u-optic.com/Show/?id=177&siteid=2).
Though the incident angle should be 56deg, I put the PBS with 45deg incident angle which caused such low transmissivity.

I use BS temporary instead of the PBS, and transmitted and reflected power is 5.8mW and 12.8mW for each.

One thing I have to take care is current configuration cannot separate p- ans s- polarized light.