To compatibly improve running characteristic under unbalanced voltage in an accident and high efficiency characteristic during normal running condition in an AC/DC power converting apparatus which is provided with an AC/DC power converter for converting power between the AC system and DC system.

This power converting apparatus comprises a gate control means 13 including a fixed pulse pattern mode and a variable pulse width pattern mode for controlling the gate of an AC/DC power converter 3, a phase control type controlling means 14 for controlling phase of an AC output voltage in the fixed pulse pattern mode, a PWM(Pulse Width Modulation) control type controlling means 15 for controlling a vector of an AC output voltage in the variable pulse width pattern mode, a control mode management means 16 for controlling the control mode, based on a voltage information of at least AC system 1, and detecting means 81 to 83 for detecting an input/output information of the AC/DC power converting apparatus. As a result, control is performed through combination of the fixed pulse pattern and variable pulse width pattern mode by controlling the first and second control means with a control mode management means.