According to the present invention, a highly safe moving-type radiation device can be provided. In the case of a conventional configuration using tension springs, if a spring is severed, the fragments will separate from each other permanently. Therefore, the present invention uses compression spring 8a and 8b instead. According to the spring mechanism of the present invention, even if a shaft is about to move largely in accordance with the severing of a spring, fragments of the spring, which has become stuck each other and immovable, interfere and prevent the movement of the shaft. What has been devised in the present invention is a junction spring seat that links a plurality of compression springs 8a and 8b. With this, even in cases where the compression springs 8a and 8b are linked in series, the compression springs 8a and 8b will not be buckled.