It has been desired to develop a pharmaceutical composition, which is used in agents for preventing and/or treating various diseases related to PDE10 (e.g. mental disorder and neurodegenerative disorder). The present invention provides: compounds having PDE10 inhibitory effect, in particular, compounds having a 4-heteroarylpyrazole-5-carboxylic acid amide structure represented by the following formula (I), or their pharmaceutically acceptable salts, or their solvates； pharmaceutical compositions comprising, as active ingredients, the compounds, or their pharmaceutically acceptable salts, or their solvates； and medical use of the compounds, or their pharmaceutically acceptable salts, or their solvates.
