In a multi-OS booting apparatus, when loading the second OS, contents of the second OS is prevented from being referred to by other programs. The first OS 151 loads the second boot loader 171 and the second OS image 211 into the first memory space 150 by using the first boot loader 154 (phase 2). The loaded second boot loader 171 configures the third memory space 170 including the first memory space 150 and the second memory space 160, removes the second boot loader 171 itself and the second OS image 211 from the management object of the first OS 151 by letting the second boot loader 171 to operate in the third memory space 170 (phase 3), configures the second memory space 160 in order to load the second OS 161 into it, and boots the second OS 161 in the second memory space 160. 展开▼