The invention discloses an alternating current amplifier device which comprises an operational amplifier U1, an operational amplifier U2, a capacitor C1, a resistor R1 and a diode D1, one end of the resistor R1 is respectively connected with the in-phase end of the operational amplifier U1 and an input signal Vi, the other end of the resistor R1 is respectively connected with a resistor R2 and the capacitor C1, the other end of the resistor R2 is respectively connected with the in-phase end of the operational amplifier U2 and a capacitor C2, the inverse-phase end of the operational amplifier U2 is respectively connected with the other end of the capacitor C1 and an anode of the diode D1, a cathode of the diode D1 is respectively connected with a ground capacitor C3, the output end of the operational amplifier U2 and a resistor R4, the other end of the resistor R4 is respectively connected with the inverse-phase end of the operational amplifier U1, a capacitor C4 and a resistor R3, and the other end of the resistor R3 is respectively connected with the output end of the operational amplifier U1, the other end of the capacitor C4 and the output end Vo. Direct current input is offset to serve as a common mode voltage to be connected to the inverse-phase input end of the operational amplifier U1, so direct current deviation is restrained, and the alternating current amplifier device is simple in circuit structure, low in cost, small in size and wide in applied range.