The purpose of the present invention is to provide crystals of 1-(3-chloro-5-{[4-(4-chlorothiophen-2-yl)-5-(4-cyclohexyl piperazin-1-yl) thiazol-2-yl] carbamoyl} pyridin-2-yl) piperidine-4-carboxylic acid maleic acid salt that can ensure constant quality and constant effects as a drug substance for medicines, and that can be stably supplied in mass production such as industrial production. The present invention relates to crystals of 1-(3-chloro-5-{[4-(4-chlorothiophen-2-yl)-5-(4-cyclohexyl piperazin-1-yl) thiazol-2-yl] carbamoyl} pyridin-2-yl) piperidine-4-carboxylic acid maleic acid salt with endothermic peak top temperatures in differential scanning calorimeter analysis of between approximately 229 and 232 degree C, and between approximately 300 and 303 degree C. The crystals of the present invention are with excellent oral absorption, can be stably supplied in mass production such as industrial production or the like, and can be used as an active ingredient in a pharmaceutical composition for preventing and/or treating various types of thrombocytopenia.