  We made near infrared multicolor imaging observations of a disk around Herbig
Be star HD100546 using Gemini/NICI. K (2.2\,$\mu$m), H$_2$O ice (3.06\,$\mu$m),
and L'(3.8\,$\mu$m) disk images were obtained and we found the 3.1\,$\mu$m
absorption feature in the scattered light spectrum, likely due to water ice
grains at the disk surface. We compared the observed depth of the ice
absorption feature with the disk model based on \cite{Oka2012} including water
ice photodesorption effect by stellar UV photons. The observed absorption depth
can be explained by the both disk models with/without photodesorption effect
within the measurement accuracy, but slightly favors the model with
photodesorption effects, implying that the UV photons play an important role on
the survival/destruction of ice grains at the Herbig Ae/Be disk surface.
Further improvement on the accuracy of the observations of the water ice
absorption depth is needed to constrain the disk models.
