An apparatus for generating electric power from wind energy comprising: a base; a blade unit including an upright shaft that extends axially along a pivot axis and that is mounted rotatably on said base, and at least one blade member that has a plurality of blades connected fixedly around said upright shaft and driven by wind to rotate about the pivot axis for converting wind energy into rotational kinetic energy; and a generator connected to said upright shaft of said blade unit for converting the rotational kinetic energy into electric power; a wind-collecting unit including a plurality of wind-collecting plates that are mounted pivotally on said base and that are disposed around said blades of said blade member with angular equidistance; and a control unit including a detector for detecting rotational speed of said upright shaft of said blade unit and for generating a control signal according to the rotational speed, and at least one driver coupled to said detector for receiving the control signal therefrom and responsive to the control signal for moving at least a portion of each of said wind-collecting plates between a first position, where any adjacent two of said wind-collecting plates define a wind guiding channel therebetween that has a wind inlet and a wind outlet facing said upright shaft, and that converges from said wind inlet toward said wind outlet so as to collect the wind to flow directly toward said blades, and a second position, where said wind outlet has a dimension not smaller than a dimension of said wind inlet so as to reduce an amount of the wind flowing toward said blades; characterized in that each of said wind-collecting plates includes: a first guiding segment fixedly disposed adjacent to and tapered toward said upright shaft of said blade unit, a second guiding segment disposed adjacent to and pivotable with respect to said first guiding segment, and a driving shaft extending in an axial direction parallel to the pivot axis, mounting said second guiding segment pivotally to said base, and being rotated by said driver so as to move said second guiding segment between the first and second positions. a base; a blade unit including an upright shaft that extends axially along a pivot axis and that is mounted rotatably on said base, and at least one blade member that has a plurality of blades connected fixedly around said upright shaft and driven by wind to rotate about the pivot axis for converting wind energy into rotational kinetic energy; and a generator connected to said upright shaft of said blade unit for converting the rotational kinetic energy into electric power; a wind-collecting unit including a plurality of wind-collecting plates that are mounted pivotally on said base and that are disposed around said blades of said blade member with angular equidistance; and a control unit including a detector for detecting rotational speed of said upright shaft of said blade unit and for generating a control signal according to the rotational speed, and at least one driver coupled to said detector for receiving the control signal therefrom and responsive to the control signal for moving at least a portion of each of said wind-collecting plates between a first position, where any adjacent two of said wind-collecting plates define a wind guiding channel therebetween that has a wind inlet and a wind outlet facing said upright shaft, and that converges from said wind inlet toward said wind outlet so as to collect the wind to flow directly toward said blades, and a second position, where said wind outlet has a dimension not smaller than a dimension of said wind inlet so as to reduce an amount of the wind flowing toward said blades; characterized in that each of said wind-collecting plates includes: a first guiding segment fixedly disposed adjacent to and tapered toward said upright shaft of said blade unit, a second guiding segment disposed adjacent to and pivotable with respect to said first guiding segment, and a driving shaft extending in an axial direction parallel to the pivot axis, mounting said second guiding segment pivotally to said base, and being rotated by said driver so as to move said second guiding segment between the first and second positions. a first guiding segment fixedly disposed adjacent to and tapered toward said upright shaft of said blade unit, a second guiding segment disposed adjacent to and pivotable with respect to said first guiding segment, and a driving shaft extending in an axial direction parallel to the pivot axis, mounting said second guiding segment pivotally to said base, and being rotated by said driver so as to move said second guiding segment between the first and second positions.