A fiber laser processing apparatus controls a LD drive current ILD in a power feedback control mode (FIG. 3E) such that output of a fiber laser beam FB rises substantially from zero or a value around zero to a preceding level having no substantial effect on laser processing and arrives at a desired level (PA) for the laser processing from a preceding level PB after a first time period (preceding pulse width TB) has elapsed (time point t2 of FIGS. 3A to 3F) from the start of the rising to the preceding level (time point t1 of FIGS. 3A to 3F), and this may effectively prevent occurrence of a high-peak pulse HP at the rising edge of the fiber laser beam FB (FIG. 3F).