A contact assembly for a vacuum interrupter, comprising: a fixed contact; a fixed electrode coupled to the fixed contact; a movable contact movable to a first position at which the movable contact comes into contact with the fixed contact and a second position at which the movable contact is separated from the fixed contact; a movable electrode coupled to the movable contact and movable with the movable contact, wherein a contact area (Φ1) between the movable electrode and the movable contact is smaller than a contact area between the movable contact and the fixed contact in the first position, and a contact area (Φ1) between the fixed electrode and the fixed contact is smaller than the contact area between the movable contact and the fixed contact in the first position, wherein, in performing a breaking operation a horizontal magnetic field is generated between the contacts; a contact support member installed on the circumference of the movable electrode to be in contact with the movable contact and increase the contact area (Φ2) contacting the movable contact together with the movable electrode in order to reduce stress applied to the movable contact and the movable electrode when the movable contact moves to the first position; and a contact support member installed on the circumference of the fixed electrode to be in contact with the fixed contact and increase the contact area (Φ2) contacting the fixed contact together with the fixed electrode in order to reduce stress applied to the fixed contact and the fixed electrode when the movable contact moves to the first position, wherein the contact support members (RM1, RM2) are configured as hollow tubular members allowing the movable electrode or the fixed electrode on which each is installed to pass therethrough. a fixed contact; a fixed electrode coupled to the fixed contact; a movable contact movable to a first position at which the movable contact comes into contact with the fixed contact and a second position at which the movable contact is separated from the fixed contact; a movable electrode coupled to the movable contact and movable with the movable contact, wherein a contact area (Φ1) between the movable electrode and the movable contact is smaller than a contact area between the movable contact and the fixed contact in the first position, and a contact area (Φ1) between the fixed electrode and the fixed contact is smaller than the contact area between the movable contact and the fixed contact in the first position, wherein, in performing a breaking operation a horizontal magnetic field is generated between the contacts; a contact support member installed on the circumference of the movable electrode to be in contact with the movable contact and increase the contact area (Φ2) contacting the movable contact together with the movable electrode in order to reduce stress applied to the movable contact and the movable electrode when the movable contact moves to the first position; and a contact support member installed on the circumference of the fixed electrode to be in contact with the fixed contact and increase the contact area (Φ2) contacting the fixed contact together with the fixed electrode in order to reduce stress applied to the fixed contact and the fixed electrode when the movable contact moves to the first position,