A solid-electrolyte secondary battery is provided which comprises a positive electrode, negative electrode and a solid electrolyte provided between the electrodes. The solid electrolyte contains as a matrix polymer a fluorocarbon polymer of 550,000 in weight-average molecular weight (Mw). The fluorocarbon polymer having a weight-average molecular weight of more than 550,000 shows an excellent adhesion to the active material layers of the positive and negative layers. Therefore, the high polymer solid (or gel) electrolyte adheres to the active material layers of the electrodes with a sufficient adhesive strength. A fluorocarbon polymer having a weight-average molecular weight (Mw) over 300,000 and under 550,000 may be used in combination with a fluorocarbon polymer of 550,000 or more in weight-average molecular weight to lower the viscosity for facilitating the formation of a film of the electrolyte.