In this paper, the Si vertical Hall devices ale fabricated by using standard bipolar process and investigated in terms of the opeating and noise properties. The sensitivity of device with P+ isolation dam(type B) has been increased up to about 1.2 times compared to that device without the dam also noise has been increased. With the condition of f=I[KHz], band-width 1[Hz], the resolution of magnetic-field detection were about $0.97[{mu}T]$/ type B and $1.25[{mu}T]$/ type A, respectively, thus we must consider correlation the low noise or good resolution and high sensitivity in the situation for device geometry design or even for the materials.