A tube joining device that fuses an end of a first tube and an end of a second tube by a plate-shaped cutting member that is heated, and replaces the fused end of the first tube and the fused end of the second tube and joins the fused ends in an aseptic condition, comprising: a housing in which the first tube and the second tube are set; a cassette mounting portion to which a cassette that stores the cutting member is detachably mounted; a control unit that performs operation control; and a delivery mechanism that delivers the cutting member accommodated in the cassette to a stand-by position, at which the cutting member stands by, by a command of the control unit when fusing the first tube and the second tube, characterized in that the delivery mechanism includes: a first pusher member that is provided to perform forward movement and backward movement along a delivery direction and delivers the cutting member to a first position that is set between a take-out position at which the cutting member is taken out from the cassette and the stand-by position, and a second pusher member that is provided to perform forward movement and backward movement along the delivery direction in combination with the first pusher member, and delivers the cutting member from the first position to the stand-by position, and an operation of delivering the cutting member by the first pusher member is capable of being switched to an operation of delivering the cutting member by the second pusher member in synchronization with forward movement and backward movement of the first pusher member and the second pusher member. a housing in which the first tube and the second tube are set; a cassette mounting portion to which a cassette that stores the cutting member is detachably mounted; a control unit that performs operation control; and a delivery mechanism that delivers the cutting member accommodated in the cassette to a stand-by position, at which the cutting member stands by, by a command of the control unit when fusing the first tube and the second tube, characterized in that the delivery mechanism includes: a first pusher member that is provided to perform forward movement and backward movement along a delivery direction and delivers the cutting member to a first position that is set between a take-out position at which the cutting member is taken out from the cassette and the stand-by position, and a second pusher member that is provided to perform forward movement and backward movement along the delivery direction in combination with the first pusher member, and delivers the cutting member from the first position to the stand-by position, and an operation of delivering the cutting member by the first pusher member is capable of being switched to an operation of delivering the cutting member by the second pusher member in synchronization with forward movement and backward movement of the first pusher member and the second pusher member. a first pusher member that is provided to perform forward movement and backward movement along a delivery direction and delivers the cutting member to a first position that is set between a take-out position at which the cutting member is taken out from the cassette and the stand-by position, and a second pusher member that is provided to perform forward movement and backward movement along the delivery direction in combination with the first pusher member, and delivers the cutting member from the first position to the stand-by position, and an operation of delivering the cutting member by the first pusher member is capable of being switched to an operation of delivering the cutting member by the second pusher member in synchronization with forward movement and backward movement of the first pusher member and the second pusher member.