A process for producing (meth)acrylic acid comprising the steps of: supplying a cooling medium to a crystallizer (1) from a heat source device (4A), thereby crystallizing (meth)acrylic acid from a crude (meth)acrylic acid solution; discharging the cooling medium from the crystallizer (1) and returning the cooling medium to the heat source device (4A); supplying a heating medium to the crystallizer (1) from a heat source device (4B), thereby melting the (meth)acrylic acid; and discharging the heating medium from the crystallizer (1) and returning the heating medium to the heat source device (4B); wherein temperature of the cooling medium returned to the heat source device (4A) is maintained constant by utilizing a first buffer tank (5); and temperature of the heating medium returned to the heat source device (4B) is maintained constant by utilizing a second buffer tank (6).