In a program execution device (100X), a memory (110) stores first information (101X) specifying one or more programs, and second information (102X) specifying some programs including at least one of programs to be executed by an other program execution device (100Y), out of the programs specified by the first information (101X) and the programs to be executed by the other program execution device (100Y). When an error in the other program execution device (100Y) is not detected by an error processing unit (123), an instruction processing unit (120) executes the programs specified by the first information (101X). When the error in the other program execution device (100Y) is detected by the error processing unit (123), the instruction processing unit (120) executes the programs specified by the second information (102X).