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Messier 15 (NGC 7078) is an old and metal-poor post core-collapse globularcluster which hosts a rich population of variable stars. We report new optical($gi$) and near-infrared (NIR, $JK_s$) multi-epoch observations for 129 RRLyrae, 4 Population II Cepheids (3 BL Herculis, 1 W Virginis), and 1 anomalousCepheid variable candidate in M15 obtained using the MegaCam and the WIRCaminstruments on the 3.6-m Canada-France-Hawaii Telescope. Multi-band data areused to improve the periods and classification of variable stars, and determineaccurate mean magnitudes and pulsational amplitudes from the light curvesfitted with optical and NIR templates. We derive optical and NIRperiod-luminosity relations for RR Lyrae stars which are best constrained inthe $K_s$-band, $m_{K_s} = -2.333~(0.054) \log P + 13.948~(0.015)$ with ascatter of only $0.037$ mag. Theoretical and empirical calibrations of RR Lyraeperiod-luminosity-metallicity relations are used to derive a true distancemodulus to M15: $15.196~\pm~0.026$~(statistical)~$\pm~ 0.039$~(systematic) mag.Our precise distance moduli based on RR Lyrae stars and Population II Cepheidvariables are mutually consistent and agree with recent distance measurementsin the literature based on {\it Gaia} parallaxes and other independent methods.

Optical and near-infrared pulsation properties of RR Lyrae and Population II Cepheid variables in the Messier 15 globular cluster