A guide unit of a game device moves a guide image from a generation position to a return position and thereafter moves the game image from the return position toward the generation position in a game screen, based on reference timing data indicating a reference timing at which a player should perform a game operation, to thereby indicate the reference timing to the player. A game operation detection unit detects a game operation by a player. An evaluation unit evaluates a game operation by a player, based on an operation timing at which a player performs a game operation and a reference timing indicated by the reference timing data.