The apparatus for forming a hemispherical micro-lens according to the present invention comprises a laser light oscillator 5 for irradiating laser light into one end 3a of an optical fiber 3, a far-field pattern (F.F.P.) detector 6 for detecting the shape of the F.F.P. of laser light emitted from the other end 3b of the optical fiber 3, discharge electrodes 1 for heating the end 3b of the optical fiber 3 and thereby forming a hemispherical microlens, and a discharge controller 2 for controlling the operation of the discharge electrodes 1 according to the shape of the detected F.F.P. With this apparatus, laser light is irradiated into one end surface 3a of an optical fiber 3, the other end surface 3b is heated to form a hemispherical microlens while measuring the F.F.P. of laser light emitted from this end surface 3b, and heating is halted according to the measured value of the F.F.P. It is preferable that the discharge controller 2 halt the heating operation when the diameter of the F.F.P. detected at the F.F.P. detector is approximately equal to a preset value, in particular the maximum value of the diameter of the F.F.P. This apparatus may also be applied in a case in which the ends 3b of a plurality of optical fibers arranged as an array are collectively heated and formed into hemispherical microlenses.