A free-piston type stirling engine comprising: a case charged with a working gas; a power piston which partitions the inside of the case into a first space and a second space; a displacer arranged in the first space; a communication hole provided in the power piston, which communicates the first space with the second space along a predetermined axis; a displacer rod extending from the displacer into the second space along the predetermined axis and passing through the communication hole; a first elastic supporting member arranged in the first space and elastically supporting at least one of the displacer and the displacer rod at its proximal end in the case; and a second elastic supporting member arranged in the second space and elastically supporting the displacer rod at its distal end in the case, wherein the communication hole permits movement of the displacer rod with the first space and the second space maintained in their airtight state, wherein the power piston and the displacer reciprocate along the predetermined axis with a predetermined phase difference therebetween, by means of the working gas in the first space being expanded and compressed by cooling and heating, and wherein bias forces of the first elastic supporting member and the second elastic supporting member restrict tilting of the displacer and the displacer rod with respect to the predetermined axis, characterized in that the first elastic supporting member is a leaf spring in the shape of a circular plate including an outer peripheral portion fixedly supported in the case, an inner peripheral portion fixedly supporting the displacer rod at its proximal end, and a vent hole which permits passage of the working gas along the predetermined axis. a case charged with a working gas; a power piston which partitions the inside of the case into a first space and a second space; a displacer arranged in the first space; a communication hole provided in the power piston, which communicates the first space with the second space along a predetermined axis; a displacer rod extending from the displacer into the second space along the predetermined axis and passing through the communication hole; a first elastic supporting member arranged in the first space and elastically supporting at least one of the displacer and the displacer rod at its proximal end in the case; and a second elastic supporting member arranged in the second space and elastically supporting the displacer rod at its distal end in the case, wherein the communication hole permits movement of the displacer rod with the first space and the second space maintained in their airtight state, wherein the power piston and the displacer reciprocate along the predetermined axis with a predetermined phase difference therebetween, by means of the working gas in the first space being expanded and compressed by cooling and heating, and wherein bias forces of the first elastic supporting member and the second elastic supporting member restrict tilting of the displacer and the displacer rod with respect to the predetermined axis, characterized in that the first elastic supporting member is a leaf spring in the shape of a circular plate including an outer peripheral portion fixedly supported in the case, an inner peripheral portion fixedly supporting the displacer rod at its proximal end, and a vent hole which permits passage of the working gas along the predetermined axis.