PURPOSE: An error calibration apparatus is provided to enable data communication efficiently by adding a function of reducing an interference where an error calibration signal affects a signal received or transmitted from and to an array antenna. CONSTITUTION: An array antenna(101) includes a plurality of emission elements and is connected to an error calibration signal inserting part(102) and an array receiver(103). The array receiver(103) down-converts an RF-band signal which is received by the array antenna and transferred via the error calibration signal inserting part(102), and converts the down-converted signal into a digital signal. An error calibration signal generator(104) up-converts an error calibration signal generated in a base band into an RF band and generates an error calibration signal. The error calibration signal inserting part(102) divides an RF error calibration signal by a total channel number and multiplies a predetermined weight with each channel. An error calibration coefficient estimation part(105) correlates an error calibration signal passing the array receiver to the error calibration signal generated from the generator(104) and estimates a transfer function of the receiver(103) of each channel. An error calibration part(106) multiplies an error calibration coefficient to a digital signal from the array receiver and removes different transfer function components every channel. An array beam forming part(107) points to a visit direction of different signals.