Apparatus and method for manufacturing high purity polysilicon. The apparatus includes a vacuum chamber maintaining a vacuum atmosphere; first and second electron guns disposed at an upper side of the vacuum chamber to irradiate electron beams into the vacuum chamber; a silicon melting unit placed on a first electron beam-irradiating region corresponding to the first electron gun and in which powdery raw silicon is placed and melted by the first electron beam; and a unidirectional solidification unit placed on a second electron beam-irradiating region corresponding to the second electron gun and connected to the silicon melting unit via a runner. The unidirectional solidification unit is formed at a lower part thereof with a cooling channel and is provided therein with a start block driven in a downward direction.