A communication apparatus including: a semiconductor DAA which performs line closing and opening processings; and a controller including; an adjustment controlling section which controls the semiconductor DAA such that a line voltage and a line current upon closing a line fall within a predetermined range; an adjustment-control starting section which starts the control; an adjustment-control stopping section which stops the control; and a change detecting section which detects a change of conditions of supply of the line voltage, wherein the adjustment-control starting section starts the control where the line closing processing has been performed and where the change has been detected, and wherein the adjustment-control stopping section stops the control when a predetermined length of time has passed, in at least one of where the line closing processing has been performed and the control is being performed, and where the change has been detected and the control is being performed.