A substrate processing apparatus includes a housing, a mounting table provided in the housing and configured to mount a substrate thereon, a drive mechanism provided below the mounting table so as to move the mounting table in a front-back direction between a delivering/receiving location for the substrate and a processing chamber, an ultraviolet irradiation unit configured to irradiate the substrate in the processing chamber with ultraviolet rays, a partition member provided to partition the processing chamber and a drive chamber with the drive mechanism positioned therein up and down, the partition member having a slit for allowing movement of a support supporting the mounting table, first exhaust ports formed in the drive chamber to exhaust an atmosphere in the drive chamber, and second exhaust ports formed along a lengthwise direction of the slit so as to face the slit.