An expression-varying device is disclosed. The device includes a supporting member that supports two eyeball bodies so that the eyeball bodies are free to pivot. The device also includes a connecting member that connects the two eyeball bodies, and that supports the eyeball bodies so that the eyeball bodies can pivot in synchronization in a side to side or left to right direction. The device includes a swinging mechanism that causes the connecting member to swing upward and downward and to the left and right. The swinging mechanism includes a disk in which a recessed groove is formed in a side surface of the disk and runs in a circumferential direction. The depth of the groove and distance of the groove from the center of the disk vary according to relative positions on the disk. The swinging mechanism includes a motor that causes the disk to rotate. An engaging shaft which engages with the recessed groove of the disk is formed on and protrudes from and to the side of the arm member. The arm member is driven by a driving member so that the tip end of the engaging shaft constantly contacts the bottom part of the recessed groove. The tip end of the arm member is caused to swing upward and downward and to the left and right in linkage with the recessed groove of the disk. Accordingly, the connecting member is caused to swing upward and downward and to the left and right, thus causing the two eyeball bodies to pivot so that various expressions are displayed.