A laser diode pumped solid laser comprises an optical module comprising a laser diode, a solid laser crystal, which is excited by a laser beam produced by the laser diode, and a resonator. An electronic cooling device has a cooling surface, on which the optical module is placed, and a heat radiating surface. An inner case housing houses the optical module therein on the cooling surface of the electronic cooling device. An outer case housing houses the inner case housing and the electronic cooling device therein and supports the electronic cooling device via its heat radiating surface. A temperature sensor detects the temperature in the region inside of the inner case housing. A control circuit controls the electronic cooling device in accordance with an output of the temperature sensor and thereby keeps the temperature in the region inside of the inner case housing at a predetermined target value.