The invention provides a pyrazolothiazole compound of the formula [I], or a pharmaceutically acceptable salt thereof:The compound of the invention has JAK1 inhibitory activity, and thus, immunosuppressive effect, anti-inflammatory effect and anti-proliferative effect, and is useful in the treatment of the diseases, for example, rheumatoid arthritis, inflammatory bowel disease, psoriasis and vasculitis, bronchial asthma, chronic obstructive pulmonary disease and eosinophilic sinusitis, nasal polyp.
