Bulk FinFETs and silicon-on-insulator (SOI) FinFETs were compared in terms of device structure, fundamental characteristics, speed characteristics, model, and application. Bulk FinFETs have shown several advantages over SOI FinFETs while keeping nearly the same scaling-down characteristics as those of SOI FinFETs. Compared to bulk FinFETs, SOI FinFETs could suppress any possible leakage between source and drain, and has low source/drain to substrate capacitance so that speed characteristics could be better. Since SOI FinFETs have two more corners in the bottom of the fin body than bulk FinFETs, bulk FinFETs can have less process variation. Both devices seem to have their specific applications.