Crystals of glucagon-like peptide-1 and GLP-1 analogues, and processes for preparation of crystals of GLP-1 and GLP-1 analogues. When the engine load is in a low-load zone, a relative value control is executed, wherein an actual value of a valve overlap amount of the intake valve and the exhaust valve is controlled to coincide with a target valve overlap amount obtained based on the target values. If no such storage provider is available, a new storage provider is added automatically.