We conducted a deep survey of z=7 Ly-alpha emitters (LAEs) with 13 hours of 
narrowband NB973 (centered at 9755A with FWHM=200A) imaging of the 
Subaru/XMM-Newton Deep Field, using the fully depleted CCDs newly installed 
on the Subaru/Suprime-Cam, which is twice more sensitive at ~1um than the 
previous CCDs. Reaching NB973=25.4 (5 sigma), 0.5 mag deeper than the previous 
survey that discovered a z=6.96 LAE, we detected at least two probable z=7 LAE 
candidates in addition to 8 less robust but possible candidates. Even if we 
assume that all the 10 candidates are real, the LAE number density at z=7 is 
lower than those at the later epochs, at least 16-31% and 31-52% of those at 
z=5.7 and 6.6 to the limit of L(Ly-alpha) = 6.0 x 10^42 erg/s. This number 
deficit might reflect the larger neutral hydrogen fraction at z=7, supporting 
the late reionization suggested by the previous surveys of z=5.7-7 LAEs, z~6 
quasars and z > 6 gamma-ray bursts.