A program development device for creating a user program operating on a controller that controls motion of a machine, the program development device comprising: a first storage unit that stores a default first motion control command in association with a command word; an editing unit (502, 504) that edits a motion control command corresponding to the command word according to an instruction of a user, wherein the first motion control command is a command for executing a default processing defined by a manufacturer that manufactures the controller in association with the command word, and that the edited motion control command is a command for executing a processing defined by the user in association with the command word; and a second storage unit that stores the edited motion control command as a second motion control command in association with the command word; the program development device is characterized by further comprising: a first building unit that builds a source code of the user program; and a second building unit that builds the second motion control command, wherein the first building unit: builds the source code in association with the second motion control command if the second motion control command corresponding to the command word written in the source code exists in the second storage unit, and builds the source code in association with the first motion control command if the second motion control command corresponding to the command word written in the source code does not exist in the second storage unit. a first storage unit that stores a default first motion control command in association with a command word; an editing unit (502, 504) that edits a motion control command corresponding to the command word according to an instruction of a user, wherein the first motion control command is a command for executing a default processing defined by a manufacturer that manufactures the controller in association with the command word, and that the edited motion control command is a command for executing a processing defined by the user in association with the command word; and a second storage unit that stores the edited motion control command as a second motion control command in association with the command word; the program development device is characterized by further comprising: a first building unit that builds a source code of the user program; and a second building unit that builds the second motion control command, wherein the first building unit: builds the source code in association with the second motion control command if the second motion control command corresponding to the command word written in the source code exists in the second storage unit, and builds the source code in association with the first motion control command if the second motion control command corresponding to the command word written in the source code does not exist in the second storage unit. a first building unit that builds a source code of the user program; and a second building unit that builds the second motion control command, wherein the first building unit: builds the source code in association with the second motion control command if the second motion control command corresponding to the command word written in the source code exists in the second storage unit, and builds the source code in association with the first motion control command if the second motion control command corresponding to the command word written in the source code does not exist in the second storage unit. builds the source code in association with the second motion control command if the second motion control command corresponding to the command word written in the source code exists in the second storage unit, and builds the source code in association with the first motion control command if the second motion control command corresponding to the command word written in the source code does not exist in the second storage unit.