Molecular dynamics simulations of a Lennard-Jones fluid under negative pressure are carried out to investigate the inception of vapor phase in the liquid (i.e., cavitation) and properties of liquid under negative pressure. The pressure of the system is reduced by uniform system expansion. In the case of larger expansion ratios, the nuclei of bubbles immediately appear, whereas finite waiting time is observed in case of smaller expansion ratio. This means the system reaches a kinetic limit of metastability. The nucleation rate calculated with the waiting time is 8 orders of magnitude larger than that of classical nucleation theory. Isothermal compressibility is also obtained and its density dependence is discussed.