Will PAL Games Work on an NTSC Nintendo 3DS? No

No. The Nintendo 3DS is region-locked. PAL-region games (Europe, Australia) will not run on an NTSC-region system (North America, Japan). The console will either fail to recognize the cartridge or display an error.

Some titles are released in both regions—those specific cartridges will work on either system—but a PAL-only game is incompatible with an NTSC 3DS.